diff --git a/Frontend/_reportManagement.html b/Frontend/_reportManagement.html
index 035bd8a..7b3c3c4 100644
--- a/Frontend/_reportManagement.html
+++ b/Frontend/_reportManagement.html
@@ -879,8 +879,12 @@
 
     const ElecEachTotal =
       $("li.active [name=reportTypeRadio]").data("type") === "compare";
-    if (ElecEachTotal) {
-      const [year, month] = $("#elecMonthDate").val().split("-");
+      if (ElecEachTotal) {
+        let preDate = new Date($("#elecMonthDate").val().split("-") + "-01");
+        preDate.setMonth(preDate.getMonth() - 1);
+        const [year, month] = $("#elecMonthDate").val().split("-");
+        const preYear = preDate.getFullYear();
+        const preMonth = (preDate.getMonth() + 1).toString().padStart(2, '0');
       datesColumns = [
         {
           label: "選擇月份 <br>" + `${year}${month}` + "(A)",
@@ -888,16 +892,15 @@
         },
         {
           label:
-            "前一月份 <br>" +
-            `${year}${month - 1 > 10 ? month - 1 : `0${month - 1}`}` +
+                "前一月份 <br>" +
+                `${preYear}${preMonth}` +
             "(B)",
-          value: `${year}-${month - 1 > 10 ? month - 1 : `0${month - 1}`}`,
+			value: `${preYear}-${preMonth}`,
         },
         {
           label:
             "差異比較 <br>" +
-            `${year}${month}(A)-${year}${month - 1 > 10 ? month - 1 : `0${month - 1}`
-            }(B)`,
+				`${year}${month}(A)-${preYear}${preMonth}(B)`,
           value: "last month different",
         },
         {
diff --git a/FrontendWebApi/ApiControllers/HydroMeterController.cs b/FrontendWebApi/ApiControllers/HydroMeterController.cs
index c9749ab..d30325a 100644
--- a/FrontendWebApi/ApiControllers/HydroMeterController.cs
+++ b/FrontendWebApi/ApiControllers/HydroMeterController.cs
@@ -1299,6 +1299,7 @@ namespace FrontendWebApi.ApiControllers
                 var start_month = date.ToString("MM"); // 查詢月
                 var last_year = previousYear.ToString("yyyy"); // 上個查詢年
                 var last_month = previousMonth.ToString("MM"); // 上個查詢月
+                var pre_year = previousMonth.ToString("yyyy"); // 上個查詢月(年份)
 
                 string sqlWhere = "";
                 string tag_quantity = await backendRepository.GetOneAsync<string>("select system_value from variable where system_type = 'obixConfig' and system_key = 'tag_quantity' and deleted = 0");
@@ -1329,14 +1330,14 @@ namespace FrontendWebApi.ApiControllers
                 }
 
                 string header_now = start_year + "-" + start_month;
-                string header_lastM = start_year + "-" + last_month;
+                string header_lastM = pre_year + "-" + last_month;
                 string header_lastY = last_year + "-" + start_month;
 
                 var sql = $@"
 select e.full_name building_name, a.device_number, '{header_now}' searchMT, ifnull(b.kwh_sum, 0) searchM, '{header_lastM}' lastMT, ifnull(c.kwh_sum, 0) lastM, '{header_lastY}' lastYT, ifnull(d.kwh_sum, 0) lastY
 from device a 
 left join (select device_number, sum(kwh_result) kwh_sum from archive_electric_meter_month where year(start_timestamp) = {start_year} and month(start_timestamp) = {start_month} group by device_number) b on a.device_number COLLATE utf8mb4_0900_ai_ci = b.device_number -- month1
-left join (select device_number, sum(kwh_result) kwh_sum from archive_electric_meter_month where year(start_timestamp) = {start_year} and month(start_timestamp) = {last_month} group by device_number) c on a.device_number COLLATE utf8mb4_0900_ai_ci = c.device_number -- month2
+left join (select device_number, sum(kwh_result) kwh_sum from archive_electric_meter_month where year(start_timestamp) = {pre_year} and month(start_timestamp) = {last_month} group by device_number) c on a.device_number COLLATE utf8mb4_0900_ai_ci = c.device_number -- month2
 left join (select device_number, sum(kwh_result) kwh_sum from archive_electric_meter_month where year(start_timestamp) = {last_year} and month(start_timestamp) = {start_month} group by device_number) d on a.device_number COLLATE utf8mb4_0900_ai_ci = d.device_number -- last Month
 join building e on a.device_building_tag = e.building_tag
 where {sqlWhere}