diff --git a/internal/task/task.go b/internal/task/task.go
index 3811738..e657f7b 100644
--- a/internal/task/task.go
+++ b/internal/task/task.go
@@ -73,8 +73,8 @@ type Task struct {
 
 var GlobalTaskList = []*Task{}
 var GlobalTaskMux = &sync.Mutex{}
-var GlobalDownloadSem = util.NewSemaphore(3)
-var GlobalMergeSem = util.NewSemaphore(3)
+var GlobalDownloadSem = util.NewSemaphore(5)
+var GlobalMergeSem = util.NewSemaphore(5)
 
 // cleanupTempFiles 清理任务的临时文件
 func (task *Task) cleanupTempFiles() {