diff --git a/parser/scanner.l b/parser/scanner.l
index 0364493921..82ed50740c 100644
--- a/parser/scanner.l
+++ b/parser/scanner.l
@@ -26,6 +26,7 @@ import (
 	"strings"
 	
 	"github.com/pingcap/tidb/expression"
+	"github.com/pingcap/tidb/util/stringutil"
 	mysql "github.com/pingcap/tidb/mysqldef"
 )
 
@@ -1011,7 +1012,8 @@ func (l *lexer) str(lval *yySymType, pref string) int {
 		s = strings.TrimSuffix(s, "'") + "\""
 		pref = "\""
 	} 
-	v, err := strconv.Unquote(pref + s)
+	v := stringutil.RemoveUselessBackslash(pref+s)
+	v, err := strconv.Unquote(v)
 	if err != nil {
 		v = strings.TrimSuffix(s, pref)
 	}
diff --git a/tidb_test.go b/tidb_test.go
index aa082ab6a7..2764db7eae 100644
--- a/tidb_test.go
+++ b/tidb_test.go
@@ -882,6 +882,16 @@ func (s *testSessionSuite) TestSelect(c *C) {
 	c.Assert(err, IsNil)
 	matches(c, rows, [][]interface{}{{1, nil, nil}, {2, 2, nil}})
 
+	// For issue 393
+	mustExecSQL(c, se, "drop table if exists t")
+	mustExecSQL(c, se, "create table t (b blob)")
+	mustExecSQL(c, se, `insert t values('\x01')`)
+
+	r = mustExecSQL(c, se, `select length(b) from t`)
+	row, err = r.FirstRow()
+	c.Assert(err, IsNil)
+	match(c, row, 3)
+
 }
 
 func (s *testSessionSuite) TestSubQuery(c *C) {
diff --git a/util/stringutil/string_util.go b/util/stringutil/string_util.go
new file mode 100644
index 0000000000..b1d1b346bd
--- /dev/null
+++ b/util/stringutil/string_util.go
@@ -0,0 +1,57 @@
+// Copyright 2014 The ql Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSES/QL-LICENSE file.
+
+// Copyright 2015 PingCAP, Inc.
+//
+// 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,
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package stringutil
+
+import (
+	"bytes"
+	"strings"
+)
+
+// See: https://dev.mysql.com/doc/refman/5.7/en/string-literals.html#character-escape-sequences
+const validEscapeChars = `0'"bntrz\\%_`
+
+// RemoveUselessBackslash removes backslashs which could be ignored in the string literal.
+// See: https://dev.mysql.com/doc/refman/5.7/en/string-literals.html
+// " Each of these sequences begins with a backslash (“\”), known as the escape character.
+// MySQL recognizes the escape sequences shown in Table 9.1, “Special Character Escape Sequences”.
+// For all other escape sequences, backslash is ignored. That is, the escaped character is
+// interpreted as if it was not escaped. For example, “\x” is just “x”. These sequences are case sensitive.
+// For example, “\b” is interpreted as a backspace, but “\B” is interpreted as “B”."
+func RemoveUselessBackslash(s string) string {
+	var (
+		buf bytes.Buffer
+		i   = 0
+	)
+	for i < len(s)-1 {
+		if s[i] != '\\' {
+			buf.WriteByte(s[i])
+			i++
+			continue
+		}
+		next := s[i+1]
+		if strings.IndexByte(validEscapeChars, next) != -1 {
+			buf.WriteByte(s[i])
+		}
+		buf.WriteByte(next)
+		i += 2
+	}
+	if i == len(s)-1 {
+		buf.WriteByte(s[i])
+	}
+	return buf.String()
+}
diff --git a/util/stringutil/string_util_test.go b/util/stringutil/string_util_test.go
new file mode 100644
index 0000000000..9201c63a45
--- /dev/null
+++ b/util/stringutil/string_util_test.go
@@ -0,0 +1,47 @@
+// Copyright 2015 PingCAP, Inc.
+//
+// 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,
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package stringutil
+
+import (
+	"testing"
+
+	. "github.com/pingcap/check"
+)
+
+func TestT(t *testing.T) {
+	TestingT(t)
+}
+
+var _ = Suite(&testStringUtilSuite{})
+
+type testStringUtilSuite struct {
+}
+
+func (s *testStringUtilSuite) TestRemoveUselessBackslash(c *C) {
+	table := []struct {
+		str    string
+		expect string
+	}{
+		{"xxxx", "xxxx"},
+		{`\x01`, `x01`},
+		{`\b01`, `\b01`},
+		{`\B01`, `B01`},
+		{`'\'a\''`, `'\'a\''`},
+	}
+
+	for _, t := range table {
+		x := RemoveUselessBackslash(t.str)
+		c.Assert(x, Equals, t.expect)
+	}
+}