diff --git a/fe/fe-core/src/main/java/org/apache/doris/nereids/trees/expressions/functions/scalar/NgramSearch.java b/fe/fe-core/src/main/java/org/apache/doris/nereids/trees/expressions/functions/scalar/NgramSearch.java
index f1a0524ef5c536..45d35150c92f07 100644
--- a/fe/fe-core/src/main/java/org/apache/doris/nereids/trees/expressions/functions/scalar/NgramSearch.java
+++ b/fe/fe-core/src/main/java/org/apache/doris/nereids/trees/expressions/functions/scalar/NgramSearch.java
@@ -22,6 +22,7 @@
 import org.apache.doris.nereids.trees.expressions.Expression;
 import org.apache.doris.nereids.trees.expressions.functions.ExplicitlyCastableSignature;
 import org.apache.doris.nereids.trees.expressions.functions.PropagateNullable;
+import org.apache.doris.nereids.trees.expressions.literal.IntegerLikeLiteral;
 import org.apache.doris.nereids.trees.expressions.visitor.ExpressionVisitor;
 import org.apache.doris.nereids.types.DoubleType;
 import org.apache.doris.nereids.types.IntegerType;
@@ -47,19 +48,28 @@ public class NgramSearch extends ScalarFunction
      */
     public NgramSearch(Expression arg0, Expression arg1, Expression arg2) {
         super("ngram_search", arg0, arg1, arg2);
-        if (!(arg1.isConstant())) {
+    }
+
+    /** constructor for withChildren and reuse signature */
+    private NgramSearch(ScalarFunctionParams functionParams) {
+        super(functionParams);
+    }
+
+    @Override
+    public void checkLegalityBeforeTypeCoercion() {
+        if (!child(1).isConstant()) {
             throw new AnalysisException(
                     "ngram_search(text,pattern,gram_num): pattern support const value only.");
         }
-        if (!(arg2.isConstant())) {
+        Expression gramNum = child(2);
+        if (!gramNum.isConstant()) {
             throw new AnalysisException(
                     "ngram_search(text,pattern,gram_num): gram_num support const value only.");
         }
-    }
-
-    /** constructor for withChildren and reuse signature */
-    private NgramSearch(ScalarFunctionParams functionParams) {
-        super(functionParams);
+        if (!(gramNum instanceof IntegerLikeLiteral) || ((IntegerLikeLiteral) gramNum).getIntValue() <= 0) {
+            throw new AnalysisException(
+                    "ngram_search(text,pattern,gram_num): gram_num must be a positive constant.");
+        }
     }
 
     /**
diff --git a/regression-test/suites/query_p0/sql_functions/string_functions/test_string_function.groovy b/regression-test/suites/query_p0/sql_functions/string_functions/test_string_function.groovy
index 9db9777b1c895d..30aa358015b584 100644
--- a/regression-test/suites/query_p0/sql_functions/string_functions/test_string_function.groovy
+++ b/regression-test/suites/query_p0/sql_functions/string_functions/test_string_function.groovy
@@ -536,6 +536,14 @@ suite("test_string_function", "arrow_flight_sql") {
     qt_ngram_search2 """select ngram_search('abc','abc1313131',3); """
     qt_ngram_search3 """select ngram_search('abc1313131','abc1313131',3); """
     qt_ngram_search3 """select ngram_search('1313131','abc1313131',3); """
+    test {
+        sql "select ngram_search('abc', 'abc', 0);"
+        exception "gram_num must be a positive constant"
+    }
+    test {
+        sql "select ngram_search('abc', 'abc', -1);"
+        exception "gram_num must be a positive constant"
+    }
     
 
     sql "drop table if exists test_function_ngram_search;";