diff --git a/internal/core/src/storage/ThreadPool.h b/internal/core/src/storage/ThreadPool.h
index 6b5e4cfa9fb4c..dd6098ed9df88 100644
--- a/internal/core/src/storage/ThreadPool.h
+++ b/internal/core/src/storage/ThreadPool.h
@@ -39,6 +39,13 @@ class ThreadPool {
         current_threads_size_ = 0;
         min_threads_size_ = CPU_NUM;
         max_threads_size_ = CPU_NUM * thread_core_coefficient;
+
+        // only IO pool will set large limit, but the CPU helps nothing to IO operations,
+        // we need to limit the max thread num, each thread will download 16 MiB data,
+        // it should be not greater than 256 (4GiB data) to avoid OOM and send too many requests to object storage
+        if (max_threads_size_ > 256) {
+            max_threads_size_ = 256;
+        }
         LOG_SEGCORE_INFO_ << "Init thread pool:" << name_
                           << " with min worker num:" << min_threads_size_
                           << " and max worker num:" << max_threads_size_;
diff --git a/internal/querynodev2/segments/segment_loader.go b/internal/querynodev2/segments/segment_loader.go
index 23f0a071b507c..283946f8d34a6 100644
--- a/internal/querynodev2/segments/segment_loader.go
+++ b/internal/querynodev2/segments/segment_loader.go
@@ -367,6 +367,9 @@ func (loader *segmentLoader) requestResource(ctx context.Context, infos ...*quer
 	diskCap := paramtable.Get().QueryNodeCfg.DiskCapacityLimit.GetAsUint64()
 
 	poolCap := runtime.NumCPU() * paramtable.Get().CommonCfg.HighPriorityThreadCoreCoefficient.GetAsInt()
+	if poolCap > 256 {
+		poolCap = 256
+	}
 	if loader.committedResource.WorkNum >= poolCap {
 		return resource, 0, merr.WrapErrServiceRequestLimitExceeded(int32(poolCap))
 	} else if loader.committedResource.MemorySize+memoryUsage >= totalMemory {