diff --git a/pkg/scheduler/framework/plugins/podtopologyspread/common.go b/pkg/scheduler/framework/plugins/podtopologyspread/common.go
index 55f8d1e42b3..3cd929f9984 100644
--- a/pkg/scheduler/framework/plugins/podtopologyspread/common.go
+++ b/pkg/scheduler/framework/plugins/podtopologyspread/common.go
@@ -135,10 +135,14 @@ func (pl *PodTopologySpread) filterTopologySpreadConstraints(constraints []v1.To
 
 func mergeLabelSetWithSelector(matchLabels labels.Set, s labels.Selector) labels.Selector {
 	mergedSelector := labels.SelectorFromSet(matchLabels)
-	if requirements, ok := s.Requirements(); ok {
-		for _, r := range requirements {
-			mergedSelector = mergedSelector.Add(r)
-		}
+
+	requirements, ok := s.Requirements()
+	if !ok {
+		return s
+	}
+
+	for _, r := range requirements {
+		mergedSelector = mergedSelector.Add(r)
 	}
 
 	return mergedSelector
diff --git a/pkg/scheduler/framework/plugins/podtopologyspread/filtering_test.go b/pkg/scheduler/framework/plugins/podtopologyspread/filtering_test.go
index c4ce832494d..801b538891d 100644
--- a/pkg/scheduler/framework/plugins/podtopologyspread/filtering_test.go
+++ b/pkg/scheduler/framework/plugins/podtopologyspread/filtering_test.go
@@ -1299,6 +1299,83 @@ func TestPreFilterState(t *testing.T) {
 			},
 			enableMatchLabelKeys: true,
 		},
+		{
+			name: "key in matchLabelKeys is ignored when LabelSelector is nil when feature gate enabled",
+			pod: st.MakePod().Name("p").Label("foo", "").
+				SpreadConstraint(1, "zone", v1.DoNotSchedule, nil, nil, nil, nil, []string{"bar"}).
+				Obj(),
+			nodes: []*v1.Node{
+				st.MakeNode().Name("node-a").Label("zone", "zone1").Label("node", "node-a").Obj(),
+				st.MakeNode().Name("node-b").Label("zone", "zone1").Label("node", "node-b").Obj(),
+				st.MakeNode().Name("node-x").Label("zone", "zone2").Label("node", "node-x").Obj(),
+				st.MakeNode().Name("node-y").Label("zone", "zone2").Label("node", "node-y").Obj(),
+			},
+			existingPods: []*v1.Pod{
+				st.MakePod().Name("p-a1").Node("node-a").Label("foo", "a").Obj(),
+				st.MakePod().Name("p-a2").Node("node-a").Label("foo", "a").Obj(),
+				st.MakePod().Name("p-b1").Node("node-b").Label("foo", "a").Obj(),
+				st.MakePod().Name("p-y1").Node("node-y").Label("foo", "a").Obj(),
+				st.MakePod().Name("p-y2").Node("node-y").Label("foo", "a").Obj(),
+			},
+			want: &preFilterState{
+				Constraints: []topologySpreadConstraint{
+					{
+						MaxSkew:            1,
+						TopologyKey:        "zone",
+						Selector:           mustConvertLabelSelectorAsSelector(t, nil),
+						MinDomains:         1,
+						NodeAffinityPolicy: v1.NodeInclusionPolicyHonor,
+						NodeTaintsPolicy:   v1.NodeInclusionPolicyIgnore,
+					},
+				},
+				TpKeyToCriticalPaths: map[string]*criticalPaths{
+					"zone": {{"zone2", 0}, {"zone1", 0}},
+				},
+				TpPairToMatchNum: map[topologyPair]int{
+					{key: "zone", value: "zone1"}: 0,
+					{key: "zone", value: "zone2"}: 0,
+				},
+			},
+			enableMatchLabelKeys: true,
+		},
+		{
+			name: "no pod is matched when LabelSelector is nil when feature gate disabled",
+			pod: st.MakePod().Name("p").Label("foo", "").
+				SpreadConstraint(1, "zone", v1.DoNotSchedule, nil, nil, nil, nil, []string{"bar"}).
+				Obj(),
+			nodes: []*v1.Node{
+				st.MakeNode().Name("node-a").Label("zone", "zone1").Label("node", "node-a").Obj(),
+				st.MakeNode().Name("node-b").Label("zone", "zone1").Label("node", "node-b").Obj(),
+				st.MakeNode().Name("node-x").Label("zone", "zone2").Label("node", "node-x").Obj(),
+				st.MakeNode().Name("node-y").Label("zone", "zone2").Label("node", "node-y").Obj(),
+			},
+			existingPods: []*v1.Pod{
+				st.MakePod().Name("p-a1").Node("node-a").Label("foo", "a").Obj(),
+				st.MakePod().Name("p-a2").Node("node-a").Label("foo", "a").Obj(),
+				st.MakePod().Name("p-b1").Node("node-b").Label("foo", "a").Obj(),
+				st.MakePod().Name("p-y1").Node("node-y").Label("foo", "a").Obj(),
+				st.MakePod().Name("p-y2").Node("node-y").Label("foo", "a").Obj(),
+			},
+			want: &preFilterState{
+				Constraints: []topologySpreadConstraint{
+					{
+						MaxSkew:            1,
+						TopologyKey:        "zone",
+						Selector:           mustConvertLabelSelectorAsSelector(t, nil),
+						MinDomains:         1,
+						NodeAffinityPolicy: v1.NodeInclusionPolicyHonor,
+						NodeTaintsPolicy:   v1.NodeInclusionPolicyIgnore,
+					},
+				},
+				TpKeyToCriticalPaths: map[string]*criticalPaths{
+					"zone": {{"zone2", 0}, {"zone1", 0}},
+				},
+				TpPairToMatchNum: map[topologyPair]int{
+					{key: "zone", value: "zone1"}: 0,
+					{key: "zone", value: "zone2"}: 0,
+				},
+			},
+		},
 		{
 			name: "key in matchLabelKeys is ignored when it isn't exist in pod.labels",
 			pod: st.MakePod().Name("p").Label("foo", "").