diff --git a/lib/box/index.ts b/lib/box/index.ts
index d2cbf7022b..4da7c69d4e 100644
--- a/lib/box/index.ts
+++ b/lib/box/index.ts
@@ -113,7 +113,7 @@ class Box extends EventEmitter {
     const src = join(this.base, path);
 
     return Cache.compareFile(
-      src.substring(ctx.base_dir.length),
+      escapeBackslash(src.substring(ctx.base_dir.length)),
       () => getHash(src),
       () => stat(src)
     ).then(result => ({
@@ -129,7 +129,7 @@ class Box extends EventEmitter {
       if (!stats.isDirectory()) return;
 
       // Check existing files in cache
-      const relativeBase = base.substring(ctx.base_dir.length);
+      const relativeBase = escapeBackslash(base.substring(ctx.base_dir.length));
       const cacheFiles = Cache.filter(item => item._id.startsWith(relativeBase)).map(item => item._id.substring(relativeBase.length));
 
       // Handle deleted files
@@ -156,12 +156,11 @@ class Box extends EventEmitter {
     });
 
     return BlueBirdPromise.reduce(this.processors, (count, processor) => {
-      // patten supports *nix style path only, replace backslashes on Windows
-      const params = processor.pattern.match(escapeBackslash(path));
+      const params = processor.pattern.match(path);
       if (!params) return count;
 
       const file = new File({
-        // source is used for file system path, keep backslashes on Windows
+        // source is used for filesystem path, keep backslashes on Windows
         source: join(base, path),
         // path is used for URL path, replace backslashes on Windows
         path: escapeBackslash(path),
@@ -195,7 +194,7 @@ class Box extends EventEmitter {
     const { base } = this;
 
     function getPath(path) {
-      return path.substring(base.length);
+      return escapeBackslash(path.substring(base.length));
     }
 
     return this.process().then(() => watch(base, this.options)).then(watcher => {
@@ -215,7 +214,7 @@ class Box extends EventEmitter {
 
       watcher.on('addDir', path => {
         let prefix = getPath(path);
-        if (prefix) prefix += sep;
+        if (prefix) prefix += '/';
 
         this._readDir(path, prefix);
       });
@@ -288,7 +287,7 @@ function readDirWalker(ctx: Hexo, base: string, results: any[], ignore: any, pre
     const prefixPath = `${prefix}${path}`;
     if (stats) {
       if (stats.isDirectory()) {
-        return readDirWalker(ctx, fullpath, results, ignore, prefixPath + sep);
+        return readDirWalker(ctx, fullpath, results, ignore, `${prefixPath}/`);
       }
       if (!isIgnoreMatch(fullpath, ignore)) {
         results.push(prefixPath);
diff --git a/lib/plugins/processor/asset.ts b/lib/plugins/processor/asset.ts
index 48ccd1401d..c56ff62052 100644
--- a/lib/plugins/processor/asset.ts
+++ b/lib/plugins/processor/asset.ts
@@ -109,7 +109,7 @@ function processPage(ctx: Hexo, file: _File) {
 }
 
 function processAsset(ctx: Hexo, file: _File) {
-  const id = relative(ctx.base_dir, file.source);
+  const id = relative(ctx.base_dir, file.source).replace(/\\/g, '/');
   const Asset = ctx.model('Asset');
   const doc = Asset.findById(id);
 
diff --git a/lib/plugins/processor/post.ts b/lib/plugins/processor/post.ts
index 969fad87a1..856fff5ba2 100644
--- a/lib/plugins/processor/post.ts
+++ b/lib/plugins/processor/post.ts
@@ -240,7 +240,7 @@ function scanAssetDir(ctx: Hexo, post) {
     if (err && err.code === 'ENOENT') return [];
     throw err;
   }).filter(item => !isExcludedFile(item, ctx.config)).map(item => {
-    const id = join(assetDir, item).substring(baseDirLength);
+    const id = join(assetDir, item).substring(baseDirLength).replace(/\\/g, '/');
     const renderablePath = id.substring(sourceDirLength + 1);
     const asset = PostAsset.findById(id);
 
@@ -274,7 +274,7 @@ function shouldSkipAsset(ctx: Hexo, post, asset) {
 function processAsset(ctx: Hexo, file: _File) {
   const PostAsset = ctx.model('PostAsset');
   const Post = ctx.model('Post');
-  const id = file.source.substring(ctx.base_dir.length);
+  const id = file.source.substring(ctx.base_dir.length).replace(/\\/g, '/');
   const postAsset = PostAsset.findById(id);
 
   if (file.type === 'delete' || Post.length === 0) {
diff --git a/lib/theme/processors/source.ts b/lib/theme/processors/source.ts
index c82d4352c9..ac8c21a1fe 100644
--- a/lib/theme/processors/source.ts
+++ b/lib/theme/processors/source.ts
@@ -4,7 +4,7 @@ import type { _File } from '../../box';
 
 function process(file: _File) {
   const Asset = this.model('Asset');
-  const id = file.source.substring(this.base_dir.length);
+  const id = file.source.substring(this.base_dir.length).replace(/\\/g, '/');
   const { path } = file.params;
   const doc = Asset.findById(id);
 
diff --git a/test/scripts/box/box.ts b/test/scripts/box/box.ts
index 55331677f2..d6d3d35b57 100644
--- a/test/scripts/box/box.ts
+++ b/test/scripts/box/box.ts
@@ -120,7 +120,7 @@ describe('Box', () => {
     const box = newBox('test');
     const name = 'a.txt';
     const path = join(box.base, name);
-    const cacheId = join('test/', name);
+    const cacheId = 'test/' + name;
 
     const processor = spy();
     box.addProcessor(processor);
@@ -144,7 +144,7 @@ describe('Box', () => {
     const box = newBox('test');
     const name = 'a.txt';
     const path = join(box.base, name);
-    const cacheId = join('test/', name);
+    const cacheId = 'test/' + name;
 
     const processor = spy();
     box.addProcessor(processor);
@@ -167,7 +167,7 @@ describe('Box', () => {
     const box = newBox('test');
     const name = 'a.txt';
     const path = join(box.base, name);
-    const cacheId = join('test/', name);
+    const cacheId = 'test/' + name;
 
     const processor = spy();
     box.addProcessor(processor);
@@ -190,7 +190,7 @@ describe('Box', () => {
     const box = newBox('test');
     const name = 'a.txt';
     const path = join(box.base, name);
-    const cacheId = join('test/', name);
+    const cacheId = 'test/' + name;
 
     const processor = spy();
     box.addProcessor(processor);
@@ -211,8 +211,7 @@ describe('Box', () => {
 
   it('process() - delete', async () => {
     const box = newBox('test');
-    // join will replace backslashes on Windows
-    const cacheId = join('test/', 'a.txt');
+    const cacheId = 'test/a.txt';
 
     const processor = spy();
     box.addProcessor(processor);
diff --git a/test/scripts/processors/asset.ts b/test/scripts/processors/asset.ts
index 127c9df08f..1e78bc44b1 100644
--- a/test/scripts/processors/asset.ts
+++ b/test/scripts/processors/asset.ts
@@ -80,7 +80,7 @@ describe('asset', () => {
 
     await writeFile(file.source, 'foo');
     await process(file);
-    const id = join('source/', file.path);
+    const id = 'source/' + file.path;
     const asset = Asset.findById(id);
 
     asset._id.should.eql(id);
@@ -103,7 +103,7 @@ describe('asset', () => {
 
     await writeFile(file.source, 'foo');
     await process(file);
-    const id = join('../source/', 'foo.jpg'); // The id should a relative path, because the 'lib/models/assets.js' use asset path by joining base path with "_id" directly.
+    const id = '../source/foo.jpg'; // The id should a relative path,because the 'lib/models/assets.js' use asset path by joining base path with "_id" directly.
     const asset = Asset.findById(id);
     asset._id.should.eql(id);
     asset.path.should.eql(file.path);
@@ -122,7 +122,7 @@ describe('asset', () => {
       renderable: false
     });
 
-    const id = join('source/', file.path);
+    const id = 'source/' + file.path;
 
     await Promise.all([
       writeFile(file.source, 'test'),
@@ -153,7 +153,7 @@ describe('asset', () => {
       renderable: false
     });
 
-    const id = join('source/', file.path);
+    const id = 'source/' + file.path;
 
     await Promise.all([
       writeFile(file.source, 'test'),
@@ -179,7 +179,7 @@ describe('asset', () => {
       renderable: false
     });
 
-    const id = join('source/', file.path);
+    const id = 'source/' + file.path;
 
     await Asset.insert({
       _id: id,
@@ -197,7 +197,7 @@ describe('asset', () => {
       renderable: false
     });
 
-    const id = join('source/', file.path);
+    const id = 'source/' + file.path;
     await process(file);
 
     should.not.exist(Asset.findById(id));
diff --git a/test/scripts/processors/post.ts b/test/scripts/processors/post.ts
index 9fa83192e2..e3f1ff54c0 100644
--- a/test/scripts/processors/post.ts
+++ b/test/scripts/processors/post.ts
@@ -118,7 +118,7 @@ describe('post', () => {
     });
 
     await process(file);
-    const id = join('source/', file.path);
+    const id = 'source/' + file.path;
     should.not.exist(PostAsset.findById(id));
   });
 
@@ -141,7 +141,7 @@ describe('post', () => {
     const postId = doc._id;
     await process(file);
 
-    const id = join('source/', file.path);
+    const id = 'source/' + file.path;
     const asset = PostAsset.findById(id);
 
     asset._id.should.eql(id);
@@ -165,7 +165,7 @@ describe('post', () => {
       renderable: false
     });
 
-    const id = join('source/', file.path);
+    const id = 'source/' + file.path;
 
     const post = await Post.insert({
       source: '_posts/foo.html',
@@ -200,7 +200,7 @@ describe('post', () => {
       renderable: false
     });
 
-    const id = join('source/', file.path);
+    const id = 'source/' + file.path;
 
     const post = await Post.insert({
       source: '_posts/foo.html',
@@ -235,7 +235,7 @@ describe('post', () => {
       renderable: false
     });
 
-    const id = join('source/', file.path);
+    const id = 'source/' + file.path;
 
     const post = await Post.insert({
       source: '_posts/foo.html',
@@ -265,7 +265,7 @@ describe('post', () => {
       renderable: false
     });
 
-    const id = join('source/', file.path);
+    const id = 'source/' + file.path;
 
     const post = await Post.insert({
       source: '_posts/foo.html',
@@ -290,7 +290,7 @@ describe('post', () => {
       renderable: false
     });
 
-    const id = join('source/', file.path);
+    const id = 'source/' + file.path;
 
     await writeFile(file.source, 'test');
     await process(file);
@@ -309,7 +309,7 @@ describe('post', () => {
       renderable: false
     });
 
-    const id = join('source/', file.path);
+    const id = 'source/' + file.path;
 
     await Promise.all([
       writeFile(file.source, 'test'),
@@ -992,7 +992,7 @@ describe('post', () => {
       '_fizz.jpg',
       '_buzz.jpg'
     ].map(filename => {
-      const id = join('source/_posts/foo/', filename);
+      const id = `source/_posts/foo/${filename}`;
       const path = join(hexo.base_dir, id);
       const contents = filename.replace(/\.\w+$/, '');
       return {
@@ -1048,8 +1048,7 @@ describe('post', () => {
       renderable: true
     });
 
-    // join will replace backslashes on Windows
-    const assetId = join('source/_posts/foo/', 'bar.jpg');
+    const assetId = 'source/_posts/foo/bar.jpg';
     const assetPath = join(hexo.base_dir, assetId);
 
     await Promise.all([
@@ -1095,8 +1094,7 @@ describe('post', () => {
       renderable: true
     });
 
-    // join will replace backslashes on Windows
-    const assetId = join('source/_posts/foo/', 'bar.jpg');
+    const assetId = 'source/_posts/foo/bar.jpg';
     const assetPath = join(hexo.base_dir, assetId);
 
     await Promise.all([
@@ -1134,8 +1132,7 @@ describe('post', () => {
       renderable: true
     });
 
-    // join will replace backslashes on Windows
-    const assetId = join('source/_posts/foo/', 'bar.jpg');
+    const assetId = 'source/_posts/foo/bar.jpg';
     const assetPath = join(hexo.base_dir, assetId);
 
     await Promise.all([
@@ -1312,7 +1309,7 @@ describe('post', () => {
       writeFile(assetFile.source, 'test')
     ]);
     await process(file);
-    const id = join('source/', assetFile.path);
+    const id = 'source/' + assetFile.path;
     const post = Post.findOne({ source: file.path });
     PostAsset.findById(id).renderable.should.be.true;
 
@@ -1348,7 +1345,7 @@ describe('post', () => {
       writeFile(assetFile.source, 'test')
     ]);
     await process(file);
-    const id = join('source/', assetFile.path);
+    const id = 'source/' + assetFile.path;
     const post = Post.findOne({ source: file.path });
     PostAsset.findById(id).renderable.should.be.false;
 
diff --git a/test/scripts/theme_processors/source.ts b/test/scripts/theme_processors/source.ts
index 5d9343b239..9b4f6f2979 100644
--- a/test/scripts/theme_processors/source.ts
+++ b/test/scripts/theme_processors/source.ts
@@ -56,7 +56,7 @@ describe('source', () => {
       type: 'create'
     });
 
-    const id = join('themes/test/', file.path);
+    const id = 'themes/test/' + file.path;
 
     await writeFile(file.source, 'test');
     await process(file);
@@ -77,7 +77,7 @@ describe('source', () => {
       type: 'update'
     });
 
-    const id = join('themes/test/', file.path);
+    const id = 'themes/test/' + file.path;
 
     await Promise.all([
       writeFile(file.source, 'test'),
@@ -104,7 +104,7 @@ describe('source', () => {
       type: 'skip'
     });
 
-    const id = join('themes/test/', file.path);
+    const id = 'themes/test/' + file.path;
 
     await Promise.all([
       writeFile(file.source, 'test'),
@@ -130,7 +130,7 @@ describe('source', () => {
       type: 'delete'
     });
 
-    const id = join('themes/test/', file.path);
+    const id = 'themes/test/' + file.path;
 
     await Asset.insert({
       _id: id,
@@ -146,7 +146,7 @@ describe('source', () => {
       type: 'delete'
     });
 
-    const id = join('themes/test/', file.path);
+    const id = 'themes/test/' + file.path;
 
     await process(file);
     should.not.exist(Asset.findById(id));