diff --git a/src/main/java/com/alibaba/druid/sql/dialect/postgresql/visitor/PGOutputVisitor.java b/src/main/java/com/alibaba/druid/sql/dialect/postgresql/visitor/PGOutputVisitor.java
index 03363a5025..69fcde9ee2 100644
--- a/src/main/java/com/alibaba/druid/sql/dialect/postgresql/visitor/PGOutputVisitor.java
+++ b/src/main/java/com/alibaba/druid/sql/dialect/postgresql/visitor/PGOutputVisitor.java
@@ -3029,4 +3029,12 @@ public class PGOutputVisitor extends SQLASTOutputVisitor implements PGASTVisitor
         printAndAccept(x.getColumns(), ", ");
         return false;
     }
+
+    protected void visitAggreateRest(SQLAggregateExpr x) {
+        SQLOrderBy orderBy = x.getWithinGroup();
+        if (orderBy != null) {
+            print(' ');
+            orderBy.accept(this);
+        }
+    }
 }
diff --git a/src/main/java/com/alibaba/druid/sql/parser/SQLExprParser.java b/src/main/java/com/alibaba/druid/sql/parser/SQLExprParser.java
index 3391696d55..033ab09529 100644
--- a/src/main/java/com/alibaba/druid/sql/parser/SQLExprParser.java
+++ b/src/main/java/com/alibaba/druid/sql/parser/SQLExprParser.java
@@ -1099,13 +1099,30 @@ public class SQLExprParser extends SQLParser {
             methodInvokeExpr.setUsing(using);
         }
 
+        SQLAggregateExpr aggregateExpr = null;
+        if (lexer.token == Token.ORDER) {
+            lexer.nextToken();
+            accept(Token.BY);
+
+            aggregateExpr = new SQLAggregateExpr(methodName);
+            aggregateExpr.getArguments().addAll(methodInvokeExpr.getParameters());
+
+            SQLOrderBy orderBy = new SQLOrderBy();
+            this.orderBy(orderBy.getItems(), orderBy);
+            aggregateExpr.setWithinGroup(orderBy);
+        }
+
         accept(Token.RPAREN);
 
         if (lexer.token == Token.OVER) {
-            SQLAggregateExpr aggregateExpr = new SQLAggregateExpr(methodName);
-            aggregateExpr.getArguments().addAll(methodInvokeExpr.getParameters());
+            if (aggregateExpr == null) {
+                aggregateExpr = new SQLAggregateExpr(methodName);
+                aggregateExpr.getArguments().addAll(methodInvokeExpr.getParameters());
+            }
             over(aggregateExpr);
+        }
 
+        if (aggregateExpr != null) {
             return primaryRest(aggregateExpr);
         }
 
diff --git a/src/main/java/com/alibaba/druid/sql/visitor/SQLASTOutputVisitor.java b/src/main/java/com/alibaba/druid/sql/visitor/SQLASTOutputVisitor.java
index dcb44b5a61..adf20669b6 100644
--- a/src/main/java/com/alibaba/druid/sql/visitor/SQLASTOutputVisitor.java
+++ b/src/main/java/com/alibaba/druid/sql/visitor/SQLASTOutputVisitor.java
@@ -1516,11 +1516,13 @@ public class SQLASTOutputVisitor extends SQLASTVisitorAdapter implements Paramet
 
         print(')');
 
-        SQLOrderBy withGroup = x.getWithinGroup();
-        if (withGroup != null) {
-            print0(ucase ? " WITHIN GROUP (" : " within group (");
-            visit(withGroup);
-            print(')');
+        if (!JdbcConstants.POSTGRESQL.equals(dbType)) {
+            SQLOrderBy withGroup = x.getWithinGroup();
+            if (withGroup != null) {
+                print0(ucase ? " WITHIN GROUP (" : " within group (");
+                visit(withGroup);
+                print(')');
+            }
         }
 
         SQLKeep keep = x.getKeep();
diff --git a/src/test/java/com/alibaba/druid/bvt/sql/postgresql/select/PGSelectTest70_string_agg.java b/src/test/java/com/alibaba/druid/bvt/sql/postgresql/select/PGSelectTest70_string_agg.java
new file mode 100644
index 0000000000..697c16358c
--- /dev/null
+++ b/src/test/java/com/alibaba/druid/bvt/sql/postgresql/select/PGSelectTest70_string_agg.java
@@ -0,0 +1,54 @@
+/*
+ * Copyright 1999-2017 Alibaba Group Holding Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.alibaba.druid.bvt.sql.postgresql.select;
+
+import com.alibaba.druid.sql.SQLUtils;
+import com.alibaba.druid.sql.ast.SQLStatement;
+import com.alibaba.druid.sql.visitor.SchemaStatVisitor;
+import com.alibaba.druid.util.JdbcConstants;
+import junit.framework.TestCase;
+
+import java.util.List;
+
+public class PGSelectTest70_string_agg extends TestCase {
+    private final String dbType = JdbcConstants.POSTGRESQL;
+
+    public void test_0() throws Exception {
+        String sql = "SELECT string_agg(a, ',' ORDER BY a) FROM table;";
+        System.out.println(sql);
+
+        List<SQLStatement> stmtList = SQLUtils.parseStatements(sql, dbType);
+        SQLStatement stmt = stmtList.get(0);
+
+        assertEquals("SELECT string_agg(a, ',' ORDER BY a)\n" +
+                "FROM table;", SQLUtils.toPGString(stmt));
+        
+        assertEquals("select string_agg(a, ',' order by a)\n" +
+                "from table;", SQLUtils.toPGString(stmt, SQLUtils.DEFAULT_LCASE_FORMAT_OPTION));
+
+        assertEquals(1, stmtList.size());
+
+        SchemaStatVisitor visitor = SQLUtils.createSchemaStatVisitor(dbType);
+        stmt.accept(visitor);
+
+//        System.out.println("Tables : " + visitor.getTables());
+        System.out.println("fields : " + visitor.getColumns());
+//        System.out.println("coditions : " + visitor.getConditions());
+
+        assertEquals(1, visitor.getColumns().size());
+        assertEquals(1, visitor.getTables().size());
+    }
+}