diff --git a/internal/logic/billing/currency.go b/internal/logic/billing/currency.go
index da5e593..5225e31 100644
--- a/internal/logic/billing/currency.go
+++ b/internal/logic/billing/currency.go
@@ -3,12 +3,12 @@ package billing
 import (
 	"context"
 
-	"github.com/shopspring/decimal"
 	lcommon "github.com/qianfree/team-api/internal/logic/common"
+	"github.com/shopspring/decimal"
 )
 
 const defaultCNYToUSD = 0.14
-const defaultUSDToCNY = 7.25
+const defaultUSDToCNY = 7.142857142857143 // 1 / 0.14，确保互为倒数
 
 // ConvertCNYToUSD 将人民币金额转换为美元，向上取整到小数点后 6 位（decimal 原生版）。
 // 用 decimal 精确乘法替代 float64 链式运算，避免 cnyAmount×rate 的浮点误差。
@@ -34,12 +34,11 @@ func GetExchangeRateCNYToUSD(ctx context.Context) float64 {
 	return rate
 }
 
-// GetExchangeRateUSDToCNY 获取 USD→CNY 兑换比例
+// GetExchangeRateUSDToCNY 获取 USD→CNY 兑换比例（取 CNY→USD 的倒数，确保往返闭合）
 func GetExchangeRateUSDToCNY(ctx context.Context) float64 {
-	cfg := lcommon.Config()
-	rate := cfg.GetFloat(ctx, "payment_exchange_rate_usd_to_cny")
+	rate := GetExchangeRateCNYToUSD(ctx)
 	if rate <= 0 {
 		return defaultUSDToCNY
 	}
-	return rate
+	return 1.0 / rate
 }
diff --git a/internal/logic/billing/currency_test.go b/internal/logic/billing/currency_test.go
index 8d91180..071fa30 100644
--- a/internal/logic/billing/currency_test.go
+++ b/internal/logic/billing/currency_test.go
@@ -2,6 +2,9 @@ package billing
 
 import (
 	"testing"
+
+	"github.com/gogf/gf/v2/test/gtest"
+	"github.com/shopspring/decimal"
 )
 
 func TestDefaultCNYToUSD(t *testing.T) {
@@ -17,7 +20,8 @@ func TestDefaultUSDToCNY(t *testing.T) {
 }
 
 func TestDefaultRates_Reciprocal(t *testing.T) {
-	// 两个默认汇率不应精确互为倒数（市场汇率有买卖价差），但数量级应一致
+	// 修复后：defaultUSDToCNY 不再是独立配置，而是 defaultCNYToUSD 的倒数
+	// 验证常量定义互为倒数
 	product := defaultCNYToUSD * defaultUSDToCNY
 	if product < 0.9 || product > 1.1 {
 		t.Fatalf("default rate product should be ~1.0, got %f", product)
@@ -77,13 +81,63 @@ func TestCurrencyConstants_NonZero(t *testing.T) {
 	}
 }
 
-func TestCurrencyConstants_ReasonableRange(t *testing.T) {
-	// CNY→USD 应在 0.1~0.2 范围内（合理汇率区间）
-	if defaultCNYToUSD < 0.05 || defaultCNYToUSD > 0.3 {
-		t.Errorf("defaultCNYToUSD %f outside reasonable range [0.05, 0.3]", defaultCNYToUSD)
+// TestExchangeRateReciprocal 验证 USD→CNY 汇率是 CNY→USD 的倒数（往返闭合）
+func TestExchangeRateReciprocal(t *testing.T) {
+	// 测试默认汇率互为倒数
+	reciprocal := 1.0 / defaultCNYToUSD
+	diff := reciprocal - defaultUSDToCNY
+	if diff < 0 {
+		diff = -diff
 	}
-	// USD→CNY 应在 5~15 范围内
-	if defaultUSDToCNY < 5 || defaultUSDToCNY > 15 {
-		t.Errorf("defaultUSDToCNY %f outside reasonable range [5, 15]", defaultUSDToCNY)
+	// 允许误差 0.01（因为默认常量可能不完全精确）
+	if diff > 0.01 {
+		t.Errorf("默认汇率应互为倒数：1/%.4f = %.4f, 但 defaultUSDToCNY = %.4f, 差值 = %.6f",
+			defaultCNYToUSD, reciprocal, defaultUSDToCNY, diff)
+	}
+}
+
+// TestConvertRoundTrip 验证 CNY→USD→CNY 往返转换闭合（误差在可接受范围内）
+func TestConvertRoundTrip(t *testing.T) {
+	gtest.C(t, func(t *gtest.T) {
+		// 测试多个典型金额
+		testAmounts := []float64{100.0, 50.5, 1.0, 999.99}
+
+		for _, originalCNY := range testAmounts {
+			// CNY → USD（使用默认汇率模拟）
+			usd := decimal.NewFromFloat(originalCNY).Mul(decimal.NewFromFloat(defaultCNYToUSD))
+
+			// USD → CNY（使用倒数）
+			cny := usd.Mul(decimal.NewFromFloat(1.0 / defaultCNYToUSD))
+
+			// 验证往返误差 < 0.01 元（1分钱）
+			diff := cny.Sub(decimal.NewFromFloat(originalCNY)).Abs()
+			t.AssertLT(InexactFloat64(diff), 0.01)
+		}
+	})
+}
+
+// TestConvertCNYToUSD_Precision 验证 CNY→USD 转换的精度（使用默认汇率）
+func TestConvertCNYToUSD_Precision(t *testing.T) {
+	// 100 CNY × 0.14 = 14 USD
+	usd := decimal.NewFromFloat(100.0).Mul(decimal.NewFromFloat(defaultCNYToUSD))
+	expected := decimal.NewFromFloat(14.0)
+
+	diff := usd.Sub(expected).Abs()
+	if InexactFloat64(diff) > 0.000001 {
+		t.Errorf("100 CNY 应转换为约 14 USD，实际=%s, 误差=%s", usd.String(), diff.String())
+	}
+}
+
+// TestConvertUSDToCNY_Precision 验证 USD→CNY 转换的精度（使用倒数）
+func TestConvertUSDToCNY_Precision(t *testing.T) {
+	// 14 USD × (1/0.14) ≈ 100 CNY
+	usd := decimal.NewFromFloat(14.0)
+	reciprocalRate := 1.0 / defaultCNYToUSD
+	cny := usd.Mul(decimal.NewFromFloat(reciprocalRate))
+	expected := decimal.NewFromFloat(100.0)
+
+	diff := cny.Sub(expected).Abs()
+	if InexactFloat64(diff) > 0.01 {
+		t.Errorf("14 USD 应转换为约 100 CNY，实际=%s, 误差=%s", cny.String(), diff.String())
 	}
 }
diff --git a/internal/logic/common/settings_registry.go b/internal/logic/common/settings_registry.go
index 1b93fcf..8c6d11a 100644
--- a/internal/logic/common/settings_registry.go
+++ b/internal/logic/common/settings_registry.go
@@ -157,9 +157,7 @@ var Registry = []SettingDef{
 	{Key: "payment_callback_base_url", Type: SettingTypeString, Default: "", Category: "payment",
 		Label: "支付回调基础URL", Description: "为空则使用请求 Host"},
 	{Key: "payment_exchange_rate_cny_to_usd", Type: SettingTypeFloat, Default: "0.14", Category: "payment",
-		Label: "CNY → USD 兑换比例", Description: "1 人民币兑换多少美元", Validation: "min:0.001,max:100"},
-	{Key: "payment_exchange_rate_usd_to_cny", Type: SettingTypeFloat, Default: "7.25", Category: "payment",
-		Label: "USD → CNY 兑换比例", Description: "1 美元兑换多少人民币", Validation: "min:0.001,max:1000"},
+		Label: "CNY → USD 兑换比例", Description: "1 人民币兑换多少美元（USD → CNY 自动取倒数，确保往返闭合）", Validation: "min:0.001,max:100"},
 
 	// ── Performance ──
 	{Key: "global_qps_limit", Type: SettingTypeInt, Default: "10000", Category: "performance",
diff --git a/web/admin/src/views/system/settings/PaymentTab.vue b/web/admin/src/views/system/settings/PaymentTab.vue
index 58c34d4..2560092 100644
--- a/web/admin/src/views/system/settings/PaymentTab.vue
+++ b/web/admin/src/views/system/settings/PaymentTab.vue
@@ -1,19 +1,22 @@
 <script setup lang="ts">
+import { computed } from 'vue'
 import { useFormValues } from './useSettings'
 const values = useFormValues()
 
-function syncRate(direction: 'cny_to_usd' | 'usd_to_cny') {
-	if (direction === 'cny_to_usd') {
-		const usdToCny = Number(values['payment_exchange_rate_usd_to_cny'])
-		if (usdToCny > 0) {
-			values['payment_exchange_rate_cny_to_usd'] = Math.round((1 / usdToCny) * 10000) / 10000
-		}
-	} else {
-		const cnyToUsd = Number(values['payment_exchange_rate_cny_to_usd'])
-		if (cnyToUsd > 0) {
-			values['payment_exchange_rate_usd_to_cny'] = Math.round((1 / cnyToUsd) * 10000) / 10000
-		}
+// 计算 CNY→USD（直接读取存储值）
+const computedCnyToUsd = computed(() => {
+	const cnyToUsd = Number(values['payment_exchange_rate_cny_to_usd'])
+	return cnyToUsd > 0 ? cnyToUsd : 0
+})
+
+// 同步 USD→CNY 到底层存储的 CNY→USD
+function updateCnyToUsd(usdToCny: number | undefined) {
+	if (!usdToCny || usdToCny <= 0) {
+		values['payment_exchange_rate_cny_to_usd'] = 0
+		return
 	}
+	// 存储倒数（CNY→USD = 1 / USD→CNY）
+	values['payment_exchange_rate_cny_to_usd'] = 1 / usdToCny
 }
 </script>
 
@@ -46,30 +49,19 @@ function syncRate(direction: 'cny_to_usd' | 'usd_to_cny') {
 		<div class="section">
 			<div class="section-title">货币兑换</div>
 			<div class="section-grid">
-				<AFormItem label="CNY → USD" help="1 人民币兑换多少美元">
-					<div style="display: flex; align-items: center; gap: 8px; width: 100%">
-						<AInputNumber
-							:model-value="values['payment_exchange_rate_cny_to_usd'] as number"
-							@change="(v: number | undefined) => values['payment_exchange_rate_cny_to_usd'] = v ?? 0"
-							:min="0.001" :max="100" :step="0.01" :precision="4"
-							style="flex: 1"
-						/>
-						<AButton type="outline" size="small" @click="syncRate('cny_to_usd')">同步</AButton>
-					</div>
+				<AFormItem label="USD → CNY" help="1 美元兑换多少人民币（常用汇率约 7.0~7.3）" class="field-full">
+					<AInputNumber
+						:model-value="(1 / (values['payment_exchange_rate_cny_to_usd'] as number || 0.14)) as number"
+						@change="updateCnyToUsd"
+						:min="0.01" :max="1000" :step="0.01" :precision="4"
+						style="width: 100%"
+					/>
 				</AFormItem>
-				<AFormItem label="USD → CNY" help="1 美元兑换多少人民币">
-					<div style="display: flex; align-items: center; gap: 8px; width: 100%">
-						<AInputNumber
-							:model-value="values['payment_exchange_rate_usd_to_cny'] as number"
-							@change="(v: number | undefined) => values['payment_exchange_rate_usd_to_cny'] = v ?? 0"
-							:min="0.001" :max="1000" :step="0.01" :precision="4"
-							style="flex: 1"
-						/>
-						<AButton type="outline" size="small" @click="syncRate('usd_to_cny')">同步</AButton>
-					</div>
+				<AFormItem label="CNY → USD（自动计算）" help="取上方汇率的倒数，确保往返闭合" class="field-full">
+					<AInput :model-value="computedCnyToUsd.toFixed(6)" disabled style="width: 100%" />
 				</AFormItem>
 				<div class="field-full" style="font-size: 12px; color: var(--color-text-3); margin-top: -8px">
-					点击「同步」可根据另一方向的汇率自动计算当前值（取倒数）
+					💡 系统以 USD→CNY 为输入（更符合习惯），内部自动取倒数存储，确保往返换算闭合
 				</div>
 			</div>
 		</div>