diff --git a/pkg/bk-monitor-worker/internal/apm/pre_calculate/window/distributive.go b/pkg/bk-monitor-worker/internal/apm/pre_calculate/window/distributive.go
index af6d73fd1..3bb631113 100644
--- a/pkg/bk-monitor-worker/internal/apm/pre_calculate/window/distributive.go
+++ b/pkg/bk-monitor-worker/internal/apm/pre_calculate/window/distributive.go
@@ -189,6 +189,9 @@ func (w *DistributiveWindow) getSubWindowMetrics(subId int) (int, int) {
 	traceCount := 0
 	spanCount := 0
 
+	if subWindow == nil {
+		return traceCount, spanCount
+	}
 	subWindow.m.Range(func(key, value any) bool {
 		traceCount++
 		v := value.(CollectTrace)