diff --git a/src/main/java/com/openhis/web/outpatient/mapper/OrderMapper.java b/src/main/java/com/openhis/web/outpatient/mapper/OrderMapper.java
index e05fa5618..f15ba11f4 100644
--- a/src/main/java/com/openhis/web/outpatient/mapper/OrderMapper.java
+++ b/src/main/java/com/openhis/web/outpatient/mapper/OrderMapper.java
@@ -13,6 +13,9 @@ import java.util.Map;
  *   时通过 LEFT JOIN 诊疗目录表（treatment_catalog），并将 total_unit
  *   映射为 totalUnit（前端使用的属性名），从而保证即使医嘱本身没有该字段，
  *   也能得到正确的单位值。
+ *
+ *   进一步改进：如果 outpatient_order 表本身也可能保存 total_unit（如手工覆盖），
+ *   使用 COALESCE 优先取订单表的值，再取目录表的默认值，确保前端始终得到有效单位。
  */
 @Mapper
 public interface OrderMapper {
@@ -36,8 +39,8 @@ public interface OrderMapper {
         "       o.route,",
         "       o.start_date        AS startDate,",
         "       o.end_date          AS endDate,",
-        "       /* 从诊疗目录获取配置的总量单位 */",
-        "       tc.total_unit       AS totalUnit",
+        "       /* 从订单或诊疗目录获取配置的总量单位 */",
+        "       COALESCE(o.total_unit, tc.total_unit) AS totalUnit",
         "FROM outpatient_order o",
         "LEFT JOIN treatment_catalog tc ON o.item_code = tc.item_code",
         "WHERE o.patient_id = #{patientId}",