diff --git a/bms-back/bms-system/src/main/java/com/bms/price/mapper/PrcPriceSetDetailMapper.java b/bms-back/bms-system/src/main/java/com/bms/price/mapper/PrcPriceSetDetailMapper.java
index 6268e4ac..808dd931 100644
--- a/bms-back/bms-system/src/main/java/com/bms/price/mapper/PrcPriceSetDetailMapper.java
+++ b/bms-back/bms-system/src/main/java/com/bms/price/mapper/PrcPriceSetDetailMapper.java
@@ -71,7 +71,7 @@ public interface PrcPriceSetDetailMapper
         @Param("psvId") Long psvId,
         @Param("productCode") String productCode);
 
-    /** Update package freight / registration only */
+    /** Update package freight / registration; null args keep existing columns. */
     public int updateDetailPrices(
         @Param("psdId") Long psdId,
         @Param("fvValue") BigDecimal fvValue,
diff --git a/bms-back/bms-system/src/main/java/com/bms/price/service/impl/PrcPriceSetServiceImpl.java b/bms-back/bms-system/src/main/java/com/bms/price/service/impl/PrcPriceSetServiceImpl.java
index c49a46f7..9265dabd 100644
--- a/bms-back/bms-system/src/main/java/com/bms/price/service/impl/PrcPriceSetServiceImpl.java
+++ b/bms-back/bms-system/src/main/java/com/bms/price/service/impl/PrcPriceSetServiceImpl.java
@@ -917,9 +917,22 @@ public class PrcPriceSetServiceImpl implements IPrcPriceSetService
                     {
                         continue;
                     }
-                    detailMapper.updateDetailPrices(hit.getPsdId(), row.getFreightPrice(), row.getRegistrationFee());
-                    hit.setFvValue(row.getFreightPrice());
-                    hit.setFvRegistrationFee(row.getRegistrationFee());
+                    // Empty import freight/registration: do not overwrite existing detail values.
+                    BigDecimal freight = row.getFreightPrice();
+                    BigDecimal registration = row.getRegistrationFee();
+                    if (freight == null && registration == null)
+                    {
+                        continue;
+                    }
+                    detailMapper.updateDetailPrices(hit.getPsdId(), freight, registration);
+                    if (freight != null)
+                    {
+                        hit.setFvValue(freight);
+                    }
+                    if (registration != null)
+                    {
+                        hit.setFvRegistrationFee(registration);
+                    }
                     touched.add(hit.getPsdId());
                     updated++;
                 }
diff --git a/bms-back/bms-system/src/main/resources/mapper/price/PrcPriceSetDetailMapper.xml b/bms-back/bms-system/src/main/resources/mapper/price/PrcPriceSetDetailMapper.xml
index e6d4939a..a50ac8ad 100644
--- a/bms-back/bms-system/src/main/resources/mapper/price/PrcPriceSetDetailMapper.xml
+++ b/bms-back/bms-system/src/main/resources/mapper/price/PrcPriceSetDetailMapper.xml
@@ -258,11 +258,14 @@ PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
         )
     </insert>
 
+    <!-- Null means keep existing value (import empty freight/registration skips overwrite). -->
     <update id="updateDetailPrices">
         update prc_price_set_detail
-        set fv_value = #{fvValue},
-            fv_registration_fee = #{fvRegistrationFee},
+        <set>
+            <if test="fvValue != null">fv_value = #{fvValue},</if>
+            <if test="fvRegistrationFee != null">fv_registration_fee = #{fvRegistrationFee},</if>
             update_time = sysdate()
+        </set>
         where psd_id = #{psdId}
     </update>