diff --git a/hxhq-modules/hxhq-system/src/main/java/com/hxhq/business/utils/CalUnitTools.java b/hxhq-modules/hxhq-system/src/main/java/com/hxhq/business/utils/CalUnitTools.java
index ee37704..1920775 100644
--- a/hxhq-modules/hxhq-system/src/main/java/com/hxhq/business/utils/CalUnitTools.java
+++ b/hxhq-modules/hxhq-system/src/main/java/com/hxhq/business/utils/CalUnitTools.java
@@ -66,9 +66,9 @@ public class CalUnitTools {
         validateUnit(kcdw);
         validateUnit(subKcdw);
         BigDecimal kcValue = formatKc(kc);
-        BigDecimal addKcValue = formatKc(subKc);
-        addKcValue = convert(addKcValue, subKcdw, kcdw);
-        kcValue = kcValue.add(addKcValue);
+        BigDecimal subKcValue = formatKc(subKc);
+        subKcValue = convert(subKcValue, subKcdw, kcdw);
+        kcValue = kcValue.subtract(subKcValue);
 
         DecimalFormat df = new DecimalFormat("#");