diff --git a/internal/querynodev2/segments/segment_loader.go b/internal/querynodev2/segments/segment_loader.go
index b3164ab74c..a56969c67d 100644
--- a/internal/querynodev2/segments/segment_loader.go
+++ b/internal/querynodev2/segments/segment_loader.go
@@ -1026,7 +1026,7 @@ func (loader *segmentLoader) loadSealedSegment(ctx context.Context, loadInfo *qu
 		return err
 	}
 	loadFieldsIndexSpan := tr.RecordSpan()
-	metrics.QueryNodeLoadIndexLatency.WithLabelValues(fmt.Sprint(paramtable.GetNodeID())).Observe(float64(loadFieldsIndexSpan))
+	metrics.QueryNodeLoadIndexLatency.WithLabelValues(fmt.Sprint(paramtable.GetNodeID())).Observe(float64(loadFieldsIndexSpan.Milliseconds()))
 
 	// 2. complement raw data for the scalar fields without raw data
 	for fieldID, info := range indexedFieldInfos {