diff --git a/backend/internal/service/payment_config_service.go b/backend/internal/service/payment_config_service.go
index d79a46ad6b..aac1cc8e26 100644
--- a/backend/internal/service/payment_config_service.go
+++ b/backend/internal/service/payment_config_service.go
@@ -343,38 +343,87 @@ func (s *PaymentConfigService) UpdatePaymentConfig(ctx context.Context, req Upda
 			return infraerrors.BadRequest("INVALID_RECHARGE_FEE_RATE", "recharge fee rate allows at most 2 decimal places")
 		}
 	}
-	m := map[string]string{
-		SettingPaymentEnabled:                    formatBoolOrEmpty(req.Enabled),
-		SettingMinRechargeAmount:                 formatPositiveFloat(req.MinAmount),
-		SettingMaxRechargeAmount:                 formatPositiveFloat(req.MaxAmount),
-		SettingDailyRechargeLimit:                formatPositiveFloat(req.DailyLimit),
-		SettingOrderTimeoutMinutes:               formatPositiveInt(req.OrderTimeoutMin),
-		SettingMaxPendingOrders:                  formatPositiveInt(req.MaxPendingOrders),
-		SettingBalancePayDisabled:                formatBoolOrEmpty(req.BalanceDisabled),
-		SettingBalanceRechargeMult:               formatPositiveFloat(req.BalanceRechargeMultiplier),
-		SettingSubscriptionUSDToCNYRate:          formatPositiveFloatExact(req.SubscriptionUSDToCNYRate),
-		SettingRechargeFeeRate:                   formatNonNegativeFloat(req.RechargeFeeRate),
-		SettingLoadBalanceStrategy:               derefStr(req.LoadBalanceStrategy),
-		SettingProductNamePrefix:                 derefStr(req.ProductNamePrefix),
-		SettingProductNameSuffix:                 derefStr(req.ProductNameSuffix),
-		SettingHelpImageURL:                      derefStr(req.HelpImageURL),
-		SettingHelpText:                          derefStr(req.HelpText),
-		SettingCancelRateLimitOn:                 formatBoolOrEmpty(req.CancelRateLimitEnabled),
-		SettingCancelRateLimitMax:                formatPositiveInt(req.CancelRateLimitMax),
-		SettingCancelWindowSize:                  formatPositiveInt(req.CancelRateLimitWindow),
-		SettingCancelWindowUnit:                  derefStr(req.CancelRateLimitUnit),
-		SettingCancelWindowMode:                  derefStr(req.CancelRateLimitMode),
-		SettingAlipayForceQRCode:                 formatBoolOrEmpty(req.AlipayForceQRCode),
-		SettingAlipayMobilePrecreateDeepLink:     formatBoolOrEmpty(req.AlipayMobilePrecreateDeepLink),
-		SettingPaymentVisibleMethodAlipaySource:  derefStr(req.VisibleMethodAlipaySource),
-		SettingPaymentVisibleMethodWxpaySource:   derefStr(req.VisibleMethodWxpaySource),
-		SettingPaymentVisibleMethodAlipayEnabled: formatBoolOrEmpty(req.VisibleMethodAlipayEnabled),
-		SettingPaymentVisibleMethodWxpayEnabled:  formatBoolOrEmpty(req.VisibleMethodWxpayEnabled),
+	m := make(map[string]string)
+	if req.Enabled != nil {
+		m[SettingPaymentEnabled] = formatBoolOrEmpty(req.Enabled)
+	}
+	if req.MinAmount != nil {
+		m[SettingMinRechargeAmount] = formatPositiveFloat(req.MinAmount)
+	}
+	if req.MaxAmount != nil {
+		m[SettingMaxRechargeAmount] = formatPositiveFloat(req.MaxAmount)
+	}
+	if req.DailyLimit != nil {
+		m[SettingDailyRechargeLimit] = formatPositiveFloat(req.DailyLimit)
+	}
+	if req.OrderTimeoutMin != nil {
+		m[SettingOrderTimeoutMinutes] = formatPositiveInt(req.OrderTimeoutMin)
+	}
+	if req.MaxPendingOrders != nil {
+		m[SettingMaxPendingOrders] = formatPositiveInt(req.MaxPendingOrders)
 	}
 	if req.EnabledTypes != nil {
 		m[SettingEnabledPaymentTypes] = strings.Join(req.EnabledTypes, ",")
-	} else {
-		m[SettingEnabledPaymentTypes] = ""
+	}
+	if req.BalanceDisabled != nil {
+		m[SettingBalancePayDisabled] = formatBoolOrEmpty(req.BalanceDisabled)
+	}
+	if req.BalanceRechargeMultiplier != nil {
+		m[SettingBalanceRechargeMult] = formatPositiveFloat(req.BalanceRechargeMultiplier)
+	}
+	if req.SubscriptionUSDToCNYRate != nil {
+		m[SettingSubscriptionUSDToCNYRate] = formatPositiveFloatExact(req.SubscriptionUSDToCNYRate)
+	}
+	if req.RechargeFeeRate != nil {
+		m[SettingRechargeFeeRate] = formatNonNegativeFloat(req.RechargeFeeRate)
+	}
+	if req.LoadBalanceStrategy != nil {
+		m[SettingLoadBalanceStrategy] = derefStr(req.LoadBalanceStrategy)
+	}
+	if req.ProductNamePrefix != nil {
+		m[SettingProductNamePrefix] = derefStr(req.ProductNamePrefix)
+	}
+	if req.ProductNameSuffix != nil {
+		m[SettingProductNameSuffix] = derefStr(req.ProductNameSuffix)
+	}
+	if req.HelpImageURL != nil {
+		m[SettingHelpImageURL] = derefStr(req.HelpImageURL)
+	}
+	if req.HelpText != nil {
+		m[SettingHelpText] = derefStr(req.HelpText)
+	}
+	if req.CancelRateLimitEnabled != nil {
+		m[SettingCancelRateLimitOn] = formatBoolOrEmpty(req.CancelRateLimitEnabled)
+	}
+	if req.CancelRateLimitMax != nil {
+		m[SettingCancelRateLimitMax] = formatPositiveInt(req.CancelRateLimitMax)
+	}
+	if req.CancelRateLimitWindow != nil {
+		m[SettingCancelWindowSize] = formatPositiveInt(req.CancelRateLimitWindow)
+	}
+	if req.CancelRateLimitUnit != nil {
+		m[SettingCancelWindowUnit] = derefStr(req.CancelRateLimitUnit)
+	}
+	if req.CancelRateLimitMode != nil {
+		m[SettingCancelWindowMode] = derefStr(req.CancelRateLimitMode)
+	}
+	if req.AlipayForceQRCode != nil {
+		m[SettingAlipayForceQRCode] = formatBoolOrEmpty(req.AlipayForceQRCode)
+	}
+	if req.AlipayMobilePrecreateDeepLink != nil {
+		m[SettingAlipayMobilePrecreateDeepLink] = formatBoolOrEmpty(req.AlipayMobilePrecreateDeepLink)
+	}
+	if req.VisibleMethodAlipaySource != nil {
+		m[SettingPaymentVisibleMethodAlipaySource] = derefStr(req.VisibleMethodAlipaySource)
+	}
+	if req.VisibleMethodWxpaySource != nil {
+		m[SettingPaymentVisibleMethodWxpaySource] = derefStr(req.VisibleMethodWxpaySource)
+	}
+	if req.VisibleMethodAlipayEnabled != nil {
+		m[SettingPaymentVisibleMethodAlipayEnabled] = formatBoolOrEmpty(req.VisibleMethodAlipayEnabled)
+	}
+	if req.VisibleMethodWxpayEnabled != nil {
+		m[SettingPaymentVisibleMethodWxpayEnabled] = formatBoolOrEmpty(req.VisibleMethodWxpayEnabled)
 	}
 	return s.settingRepo.SetMultiple(ctx, m)
 }
diff --git a/backend/internal/service/payment_config_service_test.go b/backend/internal/service/payment_config_service_test.go
index 87b1794381..900866ef90 100644
--- a/backend/internal/service/payment_config_service_test.go
+++ b/backend/internal/service/payment_config_service_test.go
@@ -441,7 +441,12 @@ func (s *paymentConfigSettingRepoStub) GetAll(context.Context) (map[string]strin
 func (s *paymentConfigSettingRepoStub) Delete(context.Context, string) error { return nil }
 
 func TestUpdatePaymentConfig_PersistsVisibleMethodRouting(t *testing.T) {
-	repo := &paymentConfigSettingRepoStub{values: map[string]string{}}
+	repo := &paymentConfigSettingRepoStub{values: map[string]string{
+		SettingPaymentVisibleMethodAlipayEnabled: "false",
+		SettingPaymentVisibleMethodAlipaySource:  VisibleMethodSourceOfficialAlipay,
+		SettingPaymentVisibleMethodWxpayEnabled:  "true",
+		SettingPaymentVisibleMethodWxpaySource:   VisibleMethodSourceEasyPayWechat,
+	}}
 	svc := &PaymentConfigService{settingRepo: repo}
 
 	alipayEnabled := true
@@ -470,6 +475,82 @@ func TestUpdatePaymentConfig_PersistsVisibleMethodRouting(t *testing.T) {
 	}
 }
 
+func TestUpdatePaymentConfig_OmittedVisibleMethodRoutingIsPreserved(t *testing.T) {
+	wantVisibleMethods := map[string]string{
+		SettingPaymentVisibleMethodAlipayEnabled: "true",
+		SettingPaymentVisibleMethodAlipaySource:  VisibleMethodSourceEasyPayAlipay,
+		SettingPaymentVisibleMethodWxpayEnabled:  "false",
+		SettingPaymentVisibleMethodWxpaySource:   VisibleMethodSourceOfficialWechat,
+	}
+	initial := make(map[string]string, len(wantVisibleMethods))
+	for key, value := range wantVisibleMethods {
+		initial[key] = value
+	}
+	repo := &paymentConfigSettingRepoStub{values: initial}
+	svc := &PaymentConfigService{settingRepo: repo}
+
+	enabled := true
+	err := svc.UpdatePaymentConfig(context.Background(), UpdatePaymentConfigRequest{Enabled: &enabled})
+	if err != nil {
+		t.Fatalf("UpdatePaymentConfig returned error: %v", err)
+	}
+
+	visibleMethodKeys := []string{
+		SettingPaymentVisibleMethodAlipayEnabled,
+		SettingPaymentVisibleMethodAlipaySource,
+		SettingPaymentVisibleMethodWxpayEnabled,
+		SettingPaymentVisibleMethodWxpaySource,
+	}
+	for _, key := range visibleMethodKeys {
+		if _, ok := repo.updates[key]; ok {
+			t.Fatalf("omitted visible method setting %q was written", key)
+		}
+		if repo.values[key] != wantVisibleMethods[key] {
+			t.Fatalf("visible method setting %q = %q, want preserved value %q", key, repo.values[key], wantVisibleMethods[key])
+		}
+	}
+	if repo.updates[SettingPaymentEnabled] != "true" {
+		t.Fatalf("payment enabled update = %q, want true", repo.updates[SettingPaymentEnabled])
+	}
+}
+
+func TestUpdatePaymentConfig_PersistsExplicitEmptyAndFalseValues(t *testing.T) {
+	repo := &paymentConfigSettingRepoStub{values: map[string]string{
+		SettingEnabledPaymentTypes: "alipay,wxpay",
+		SettingBalancePayDisabled:  "true",
+		SettingProductNamePrefix:   "existing",
+	}}
+	svc := &PaymentConfigService{settingRepo: repo}
+
+	falseValue := false
+	emptyString := ""
+	err := svc.UpdatePaymentConfig(context.Background(), UpdatePaymentConfigRequest{
+		EnabledTypes:      []string{},
+		BalanceDisabled:   &falseValue,
+		ProductNamePrefix: &emptyString,
+	})
+	if err != nil {
+		t.Fatalf("UpdatePaymentConfig returned error: %v", err)
+	}
+
+	want := map[string]string{
+		SettingEnabledPaymentTypes: "",
+		SettingBalancePayDisabled:  "false",
+		SettingProductNamePrefix:   "",
+	}
+	if len(repo.updates) != len(want) {
+		t.Fatalf("updates = %v, want exactly %v", repo.updates, want)
+	}
+	for key, value := range want {
+		if repo.updates[key] != value {
+			t.Fatalf("update %q = %q, want %q", key, repo.updates[key], value)
+		}
+		if repo.values[key] != value {
+			t.Fatalf("stored %q = %q, want %q", key, repo.values[key], value)
+		}
+	}
+}
+
 func paymentConfigStrPtr(value string) *string {
 	return &value
 }