diff --git a/src/engine/moneySystem.js b/src/engine/moneySystem.js
new file mode 100644
index 0000000..7c8206a
--- /dev/null
+++ b/src/engine/moneySystem.js
@@ -0,0 +1,20 @@
+// ==================== 银两系统 ====================
+
+export function applyDailyIncome(state, amount) {
+  state.money += amount;
+  if (state.money < 0) {
+    state.money = 0;
+  }
+}
+
+export function canAfford(state, cost) {
+  return state.money >= cost;
+}
+
+export function spendMoney(state, amount) {
+  if (!canAfford(state, amount)) {
+    return false;
+  }
+  state.money -= amount;
+  return true;
+}
diff --git a/test/moneySystem.test.js b/test/moneySystem.test.js
new file mode 100644
index 0000000..6f810f2
--- /dev/null
+++ b/test/moneySystem.test.js
@@ -0,0 +1,72 @@
+// ==================== 银两系统测试 ====================
+
+import { applyDailyIncome, canAfford, spendMoney } from '../src/engine/moneySystem.js';
+
+let passCount = 0;
+let failCount = 0;
+
+function assert(condition, message) {
+  if (condition) {
+    passCount++;
+  } else {
+    failCount++;
+    console.error('FAIL:', message);
+  }
+}
+
+function testApplyDailyIncome() {
+  // 正收入
+  const state1 = { money: 100 };
+  applyDailyIncome(state1, 50);
+  assert(state1.money === 150, 'positive income should add to money');
+
+  // 负收入
+  const state2 = { money: 100 };
+  applyDailyIncome(state2, -30);
+  assert(state2.money === 70, 'negative income should subtract from money');
+
+  // 负收入导致归零
+  const state3 = { money: 20 };
+  applyDailyIncome(state3, -50);
+  assert(state3.money === 0, 'negative income below zero should clamp to 0');
+}
+
+function testCanAfford() {
+  // 足够
+  const state1 = { money: 100 };
+  assert(canAfford(state1, 50) === true, 'should afford when money >= cost');
+
+  // 不足够
+  const state2 = { money: 30 };
+  assert(canAfford(state2, 50) === false, 'should not afford when money < cost');
+
+  // 刚好相等
+  const state3 = { money: 50 };
+  assert(canAfford(state3, 50) === true, 'should afford when money === cost');
+}
+
+function testSpendMoney() {
+  // 成功消费
+  const state1 = { money: 100 };
+  const result1 = spendMoney(state1, 40);
+  assert(result1 === true, 'spendMoney should return true on success');
+  assert(state1.money === 60, 'money should decrease after spending');
+
+  // 余额不足
+  const state2 = { money: 30 };
+  const result2 = spendMoney(state2, 50);
+  assert(result2 === false, 'spendMoney should return false when insufficient funds');
+  assert(state2.money === 30, 'money should remain unchanged when spending fails');
+}
+
+// 运行测试
+testApplyDailyIncome();
+testCanAfford();
+testSpendMoney();
+
+if (failCount === 0) {
+  console.log('All moneySystem tests PASS');
+} else {
+  console.log(`${passCount} passed, ${failCount} failed`);
+  process.exit(1);
+}