diff --git a/go-backend/internal/http/handler/tunnel_probe_target.go b/go-backend/internal/http/handler/tunnel_probe_target.go
index 2110854..d21200f 100644
--- a/go-backend/internal/http/handler/tunnel_probe_target.go
+++ b/go-backend/internal/http/handler/tunnel_probe_target.go
@@ -4,6 +4,7 @@ import (
 	"errors"
 	"fmt"
 	"net/netip"
+	"strconv"
 	"strings"
 
 	"go-backend/internal/store/model"
@@ -135,7 +136,67 @@ func parseTunnelProbeTargetFromRequest(req map[string]interface{}) (tunnelProbeT
 	if req == nil {
 		return defaultTunnelProbeTarget(), false, nil
 	}
-	return normalizeTunnelProbeTarget(asString(req["probeTargetHost"]), asInt(req["probeTargetPort"], 0))
+	rawHost, hasHost := req["probeTargetHost"]
+	rawPort, hasPort := req["probeTargetPort"]
+	if !hasHost && !hasPort {
+		return defaultTunnelProbeTarget(), false, nil
+	}
+	host, err := parseTunnelProbeTargetHostValue(rawHost)
+	if err != nil {
+		return tunnelProbeTarget{}, false, err
+	}
+	port, err := parseTunnelProbeTargetPortValue(rawPort)
+	if err != nil {
+		return tunnelProbeTarget{}, false, err
+	}
+	return normalizeTunnelProbeTarget(host, port)
+}
+
+func parseTunnelProbeTargetHostValue(raw interface{}) (string, error) {
+	if raw == nil {
+		return "", nil
+	}
+	host, ok := raw.(string)
+	if !ok {
+		return "", errors.New("测试目标 Host 格式无效")
+	}
+	if host != strings.TrimSpace(host) {
+		return "", errors.New("测试目标 Host 不能包含协议或路径")
+	}
+	return host, nil
+}
+
+func parseTunnelProbeTargetPortValue(raw interface{}) (int, error) {
+	if raw == nil {
+		return 0, nil
+	}
+	switch v := raw.(type) {
+	case float64:
+		if v != float64(int64(v)) {
+			return 0, errors.New("测试目标端口必须是整数")
+		}
+		return int(v), nil
+	case string:
+		if v == "" {
+			return 0, nil
+		}
+		if v != strings.TrimSpace(v) {
+			return 0, errors.New("测试目标端口必须是整数")
+		}
+		port, err := strconv.Atoi(v)
+		if err != nil {
+			return 0, errors.New("测试目标端口必须是整数")
+		}
+		return port, nil
+	case int:
+		return v, nil
+	case int32:
+		return int(v), nil
+	case int64:
+		return int(v), nil
+	default:
+		return 0, errors.New("测试目标端口必须是整数")
+	}
 }
 
 func effectiveTunnelProbeTarget(tunnel *model.Tunnel) tunnelProbeTarget {
diff --git a/go-backend/internal/http/handler/tunnel_probe_target_api_test.go b/go-backend/internal/http/handler/tunnel_probe_target_api_test.go
index 01f4e8b..159076f 100644
--- a/go-backend/internal/http/handler/tunnel_probe_target_api_test.go
+++ b/go-backend/internal/http/handler/tunnel_probe_target_api_test.go
@@ -101,6 +101,53 @@ func TestTunnelUpdateWithoutProbeTargetFieldsPreservesExistingTarget(t *testing.
 	}
 }
 
+func TestTunnelUpdateRejectsInvalidProbeTargetWithoutClearingExistingTarget(t *testing.T) {
+	tests := []struct {
+		name        string
+		probeFields string
+	}{
+		{name: "non numeric port", probeFields: `,"probeTargetPort":"abc"`},
+		{name: "fractional port", probeFields: `,"probeTargetPort":443.5`},
+		{name: "whitespace host", probeFields: `,"probeTargetHost":"   "`},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			h := setupProbeTargetTunnelHandler(t)
+			seedProbeTargetTunnel(t, h, 80, "existing", "old.example.com", 9443)
+			body := bytes.NewReader([]byte(`{
+				"id":80,
+				"name":"existing",
+				"type":1,
+				"flow":1,
+				"trafficRatio":1,
+				"status":1,
+				"inNodeId":[{"nodeId":10,"protocol":"tls"}]
+			` + tt.probeFields + `}`))
+
+			res := httptest.NewRecorder()
+			h.tunnelUpdate(res, httptest.NewRequest(http.MethodPost, "/api/v1/tunnel/update", body))
+			var payload struct {
+				Code int    `json:"code"`
+				Msg  string `json:"msg"`
+			}
+			decodeProbeTargetResponse(t, res, &payload)
+			if payload.Code == 0 || payload.Msg == "" {
+				t.Fatalf("expected validation failure, got %+v", payload)
+			}
+
+			items, err := h.repo.ListTunnels()
+			if err != nil {
+				t.Fatalf("list tunnels: %v", err)
+			}
+			item := findProbeTargetTunnelItem(t, items, 80)
+			if item["probeTargetHost"] != "old.example.com" || item["probeTargetPort"] != 9443 {
+				t.Fatalf("expected invalid probe target to preserve existing target, got %+v", item)
+			}
+		})
+	}
+}
+
 func TestTunnelCreateRejectsInvalidProbeTarget(t *testing.T) {
 	h := setupProbeTargetTunnelHandler(t)
 	body := bytes.NewReader([]byte(`{