diff --git a/api/internal/core/entity/entity.go b/api/internal/core/entity/entity.go
index 4f0677034e..f7d4857057 100644
--- a/api/internal/core/entity/entity.go
+++ b/api/internal/core/entity/entity.go
@@ -156,9 +156,9 @@ type UpstreamTLS struct {
 }
 
 type UpstreamKeepalivePool struct {
-	IdleTimeout TimeoutValue `json:"idle_timeout,omitempty"`
-	Requests    int          `json:"requests,omitempty"`
-	Size        int          `json:"size"`
+	IdleTimeout *TimeoutValue `json:"idle_timeout,omitempty"`
+	Requests    int           `json:"requests,omitempty"`
+	Size        int           `json:"size"`
 }
 
 type UpstreamDef struct {
diff --git a/api/internal/core/entity/format_test.go b/api/internal/core/entity/format_test.go
index 56e2458bef..810c43dfac 100644
--- a/api/internal/core/entity/format_test.go
+++ b/api/internal/core/entity/format_test.go
@@ -180,6 +180,31 @@ func TestNodesFormat_no_nodes(t *testing.T) {
 	assert.Contains(t, jsonStr, `null`)
 }
 
+func Test_Idle_Timeout_nil_and_zero(t *testing.T) {
+	ukp0 := UpstreamKeepalivePool{}
+	// Unmarshal from zero value
+	err := json.Unmarshal([]byte(`{"idle_timeout":0}`), &ukp0)
+	assert.Nil(t, err)
+	assert.Equal(t, *ukp0.IdleTimeout, TimeoutValue(0))
+
+	// Marshal with zero value
+	marshaled, err := json.Marshal(ukp0)
+	assert.Nil(t, err)
+	assert.Contains(t, string(marshaled), `"idle_timeout":0`)
+
+	ukpNil := UpstreamKeepalivePool{}
+
+	// Unmarshal from nil value
+	err = json.Unmarshal([]byte(`{}`), &ukpNil)
+	assert.Nil(t, err)
+	assert.Nil(t, ukpNil.IdleTimeout)
+
+	// Marshal with nil value
+	marshaledNil, err := json.Marshal(ukpNil)
+	assert.Nil(t, err)
+	assert.Equal(t, string(marshaledNil), `{"size":0}`)
+}
+
 func TestUpstream_nil_and_zero_retries(t *testing.T) {
 	ud0 := UpstreamDef{}
 	// Unmarshal from zero value
diff --git a/api/test/e2enew/upstream/upstream_keepalive_pool.go b/api/test/e2enew/upstream/upstream_keepalive_pool.go
index a16ebe0ae8..21e8c50346 100644
--- a/api/test/e2enew/upstream/upstream_keepalive_pool.go
+++ b/api/test/e2enew/upstream/upstream_keepalive_pool.go
@@ -64,3 +64,86 @@ var _ = ginkgo.Describe("Upstream keepalive pool", func() {
 		})
 	})
 })
+
+// Test idle timeout zero and nil
+var _ = ginkgo.Describe("Test Upstream keepalive pool", func() {
+	ginkgo.It("create upstream with idle_timeout zero", func() {
+		base.RunTestCase(base.HttpTestCase{
+			Object: base.ManagerApiExpect(),
+			Method: http.MethodPut,
+			Path:   "/apisix/admin/upstreams/zero_idle_timeout",
+			Body: `{
+					"name":"upstream1",
+					"nodes":[{
+							"host": "` + base.UpstreamIp + `",
+							"port": 1980,
+							"weight": 1
+						}],
+					"keepalive_pool":{
+						"size":         320,
+						"requests":     1000,
+						"idle_timeout": 0
+					},
+					"type":"roundrobin"
+			}`,
+			Headers:      map[string]string{"Authorization": base.GetToken()},
+			ExpectStatus: http.StatusOK,
+		})
+	})
+
+	ginkgo.It("get upstream with idle_timeout zero", func() {
+		base.RunTestCase(base.HttpTestCase{
+			Object:       base.ManagerApiExpect(),
+			Method:       http.MethodGet,
+			Path:         "/apisix/admin/upstreams/zero_idle_timeout",
+			Headers:      map[string]string{"Authorization": base.GetToken()},
+			ExpectStatus: http.StatusOK,
+			ExpectBody:   []string{`"id":"zero_idle_timeout"`, `"idle_timeout":0`, `"name":"upstream1"`},
+		})
+	})
+
+	ginkgo.It("create upstream with idle_timeout nil", func() {
+		base.RunTestCase(base.HttpTestCase{
+			Object: base.ManagerApiExpect(),
+			Method: http.MethodPut,
+			Path:   "/apisix/admin/upstreams/nil_idle_timeout",
+			Body: `{
+					"name":"upstream2",
+					"nodes":[{
+							"host":"` + base.UpstreamIp + `",
+							"port":1980,
+							"weight":1
+					}],
+					"keepalive_pool":{
+						"size":         320,
+						"requests":     1000
+					},
+					"type":"roundrobin"
+			}`,
+			Headers:      map[string]string{"Authorization": base.GetToken()},
+			ExpectStatus: http.StatusOK,
+		})
+	})
+
+	ginkgo.It("get upstream with idle_timeout nil", func() {
+		base.RunTestCase(base.HttpTestCase{
+			Object:       base.ManagerApiExpect(),
+			Method:       http.MethodGet,
+			Path:         "/apisix/admin/upstreams/nil_idle_timeout",
+			Headers:      map[string]string{"Authorization": base.GetToken()},
+			ExpectStatus: http.StatusOK,
+			ExpectBody:   []string{`"id":"nil_idle_timeout"`, `"name":"upstream2"`},
+			UnexpectBody: []string{`"idle_timeout":0`},
+		})
+	})
+
+	ginkgo.It("delete upstream", func() {
+		base.RunTestCase(base.HttpTestCase{
+			Object:       base.ManagerApiExpect(),
+			Method:       http.MethodDelete,
+			Path:         "/apisix/admin/upstreams/zero_idle_timeout,nil_idle_timeout",
+			Headers:      map[string]string{"Authorization": base.GetToken()},
+			ExpectStatus: http.StatusOK,
+		})
+	})
+})