diff --git a/fe/fe-core/src/main/java/org/apache/doris/nereids/rules/analysis/BindFunction.java b/fe/fe-core/src/main/java/org/apache/doris/nereids/rules/analysis/BindFunction.java
index 567d2169ff..d1a4a4cd2c 100644
--- a/fe/fe-core/src/main/java/org/apache/doris/nereids/rules/analysis/BindFunction.java
+++ b/fe/fe-core/src/main/java/org/apache/doris/nereids/rules/analysis/BindFunction.java
@@ -175,7 +175,7 @@ public class BindFunction implements AnalysisRuleFactory {
                 } catch (Exception e) {
                     // ignore
                 }
-                if (!left.getDataType().isDateType() && arithmetic.getTimeUnit().isDateTimeUnit()) {
+                if (!left.getDataType().isDateType() && !arithmetic.getTimeUnit().isDateTimeUnit()) {
                     left = arithmetic.left().castTo(DateType.INSTANCE);
                 }
             }
diff --git a/fe/fe-core/src/main/java/org/apache/doris/nereids/trees/expressions/TimestampArithmetic.java b/fe/fe-core/src/main/java/org/apache/doris/nereids/trees/expressions/TimestampArithmetic.java
index ec5c5ce02f..c288698451 100644
--- a/fe/fe-core/src/main/java/org/apache/doris/nereids/trees/expressions/TimestampArithmetic.java
+++ b/fe/fe-core/src/main/java/org/apache/doris/nereids/trees/expressions/TimestampArithmetic.java
@@ -36,6 +36,7 @@ import java.util.List;
  * Describes the addition and subtraction of time units from timestamps.
  * Arithmetic expressions on timestamps are syntactic sugar.
  * They are executed as function call exprs in the BE.
+ * Example: '1996-01-01' + INTERVAL '3' month;
  * TODO: we need to rethink this, and maybe need to add a new type of Interval then implement IntervalLiteral as others
  */
 public class TimestampArithmetic extends Expression implements BinaryExpression {