diff --git a/src/actions/portfolio.ts b/src/actions/portfolio.ts
index 7cc9741..027b8a7 100644
--- a/src/actions/portfolio.ts
+++ b/src/actions/portfolio.ts
@@ -73,12 +73,13 @@ function calculateCnyValueFromPrice(
 }
 
 export async function getPortfolioPositions(): Promise<Position[]> {
-  const allTransactions = await db
+ const allTransactions = await db
     .select({
       txType: transactions.txType,
       quantity: transactions.quantity,
       price: transactions.price,
       exchangeRate: transactions.exchangeRate,
+      txCurrency: transactions.txCurrency,
       assetId: transactions.assetId,
       assetSymbol: assets.symbol,
       assetType: assets.type,
@@ -89,6 +90,14 @@ export async function getPortfolioPositions(): Promise<Position[]> {
     .leftJoin(assets, eq(assets.id, transactions.assetId))
     .orderBy(desc(transactions.executedAt));
 
+  const rates = await db.select({
+    fromCurrency: exchangeRates.fromCurrency,
+    toCurrency: exchangeRates.toCurrency,
+    rate: exchangeRates.rate,
+  }).from(exchangeRates);
+
+  const rateMap = buildRateMap(rates);
+
   const holdings = new Map<string, {
     assetId: string;
     symbol: string;
@@ -123,13 +132,27 @@ export async function getPortfolioPositions(): Promise<Position[]> {
       holding.quantity = holding.quantity.plus(new Big(tx.quantity));
       const costPerUnit = new Big(tx.quantity).times(new Big(tx.price));
       holding.totalCostNative = holding.totalCostNative.plus(costPerUnit);
-      const costCny = costPerUnit.times(new Big(tx.exchangeRate || '1'));
+      let appliedRate = tx.exchangeRate;
+      if ((!appliedRate || appliedRate === '1' || appliedRate === '1.00000000') && tx.txCurrency !== 'CNY') {
+        const fallbackRate = getRate(rateMap, tx.txCurrency, 'CNY');
+        if (fallbackRate) {
+          appliedRate = fallbackRate;
+        }
+      }
+      const costCny = costPerUnit.times(new Big(appliedRate || '1'));
       holding.totalCostCny = holding.totalCostCny.plus(costCny);
     } else if (tx.txType === 'SELL') {
       holding.quantity = holding.quantity.minus(new Big(tx.quantity));
       const sellCostPerUnit = new Big(tx.quantity).times(new Big(tx.price));
       holding.totalCostNative = holding.totalCostNative.minus(sellCostPerUnit);
-      const sellCostCny = sellCostPerUnit.times(new Big(tx.exchangeRate || '1'));
+      let appliedRate = tx.exchangeRate;
+      if ((!appliedRate || appliedRate === '1' || appliedRate === '1.00000000') && tx.txCurrency !== 'CNY') {
+        const fallbackRate = getRate(rateMap, tx.txCurrency, 'CNY');
+        if (fallbackRate) {
+          appliedRate = fallbackRate;
+        }
+      }
+      const sellCostCny = sellCostPerUnit.times(new Big(appliedRate || '1'));
       holding.totalCostCny = holding.totalCostCny.minus(sellCostCny);
     } else if (tx.txType === 'AIRDROP') {
       holding.quantity = holding.quantity.plus(new Big(tx.quantity));
@@ -142,14 +165,6 @@ export async function getPortfolioPositions(): Promise<Position[]> {
     }
   }
 
-  const rates = await db.select({
-    fromCurrency: exchangeRates.fromCurrency,
-    toCurrency: exchangeRates.toCurrency,
-    rate: exchangeRates.rate,
-  }).from(exchangeRates);
-
-  const rateMap = buildRateMap(rates);
-
   const result: Position[] = [];
   let totalCnyValue = new Big('0');
   let totalPnlCny = new Big('0');
diff --git a/src/actions/transaction.ts b/src/actions/transaction.ts
index 24ac31f..6d49a44 100644
--- a/src/actions/transaction.ts
+++ b/src/actions/transaction.ts
@@ -1,9 +1,9 @@
 'use server';
 
 import { db } from '@/db';
-import { transactions, transactionTypeEnum } from '@/db/schema';
+import { transactions, transactionTypeEnum, exchangeRates } from '@/db/schema';
 import { z } from 'zod';
-import { eq, desc } from 'drizzle-orm';
+import { eq, desc, and } from 'drizzle-orm';
 
 const createTransactionSchema = z.object({
   assetId: z.string().uuid(),
@@ -23,7 +23,21 @@ export async function createTransaction(params: z.infer<typeof createTransaction
   }
 
   try {
-    const [transaction] = await db.insert(transactions).values(validation.data).returning();
+    const data = { ...validation.data };
+    if (data.txCurrency !== 'CNY' && (!data.exchangeRate || data.exchangeRate === '1' || data.exchangeRate === '1.00000000')) {
+      const [latestRate] = await db
+        .select({ rate: exchangeRates.rate })
+        .from(exchangeRates)
+        .where(and(
+          eq(exchangeRates.fromCurrency, data.txCurrency),
+          eq(exchangeRates.toCurrency, 'CNY')
+        ))
+        .limit(1);
+      if (latestRate) {
+        data.exchangeRate = latestRate.rate;
+      }
+    }
+    const [transaction] = await db.insert(transactions).values(data).returning();
     return { success: true, data: transaction };
   } catch (error: unknown) {
     if (