diff --git a/frontend/js/trial-periods-page.js b/frontend/js/trial-periods-page.js
index 05c62b6..299e7c0 100644
--- a/frontend/js/trial-periods-page.js
+++ b/frontend/js/trial-periods-page.js
@@ -99,6 +99,15 @@ async function loadCustomersMap() {
     }
 }
 
+// Helper function to get customer name - returns friendly placeholder if not found
+function getCustomerName(customerId) {
+    if (!customerId) return '未知客户';
+    const name = customersMap[customerId];
+    if (name) return name;
+    // If ID not found in map, return shortened ID with indicator
+    return '(已删除客户)';
+}
+
 // Alias for loadCustomersMap - used by main.js when switching to trial periods section
 async function loadCustomersForDropdown() {
     return await loadCustomersMap();
@@ -173,7 +182,7 @@ function renderExpiryWarnings() {
         endTime.setHours(0, 0, 0, 0); // Set to start of day
 
         const daysUntilExpiry = Math.ceil((endTime - now) / (1000 * 60 * 60 * 24));
-        const customerName = customersMap[period.customerId] || period.customerId;
+        const customerName = getCustomerName(period.customerId);
 
         if (daysUntilExpiry >= 0 && daysUntilExpiry <= 3) {
             warnings.push({
@@ -264,7 +273,7 @@ function renderTrialPeriodsTable() {
         row.classList.add('trial-row');
 
         // 显示客户名称，如果找不到则显示ID
-        const customerName = customersMap[period.customerId] || period.customerId;
+        const customerName = getCustomerName(period.customerId);
 
         // 计算状态和到期天数
         const now = new Date();