diff --git a/expression/builtin_math.go b/expression/builtin_math.go
index db24c77015652..91ffdc16c7757 100644
--- a/expression/builtin_math.go
+++ b/expression/builtin_math.go
@@ -1029,10 +1029,10 @@ func (b *builtinRandWithSeedSig) evalReal(row chunk.Row) (float64, bool, error)
 	// builtinRandWithSeedSig, the seed is initialized with the value for each
 	// invocation of RAND().
 	var randGen *rand.Rand
-	if isNull {
-		randGen = rand.New(rand.NewSource(time.Now().UnixNano()))
-	} else {
+	if !isNull {
 		randGen = rand.New(rand.NewSource(seed))
+	} else {
+		randGen = rand.New(rand.NewSource(time.Now().UnixNano()))
 	}
 	return randGen.Float64(), false, nil
 }
diff --git a/expression/builtin_math_vec.go b/expression/builtin_math_vec.go
index def5de04b6922..b9c83fcc5eda0 100644
--- a/expression/builtin_math_vec.go
+++ b/expression/builtin_math_vec.go
@@ -17,7 +17,9 @@ import (
 	"fmt"
 	"hash/crc32"
 	"math"
+	"math/rand"
 	"strconv"
+	"time"
 
 	"github.com/cznic/mathutil"
 	"github.com/pingcap/errors"
@@ -706,11 +708,32 @@ func (b *builtinRandSig) vecEvalReal(input *chunk.Chunk, result *chunk.Column) e
 }
 
 func (b *builtinRandWithSeedSig) vectorized() bool {
-	return false
+	return true
 }
 
 func (b *builtinRandWithSeedSig) vecEvalReal(input *chunk.Chunk, result *chunk.Column) error {
-	return errors.Errorf("not implemented")
+	n := input.NumRows()
+	buf, err := b.bufAllocator.get(types.ETInt, n)
+	if err != nil {
+		return err
+	}
+	defer b.bufAllocator.put(buf)
+	if err = b.args[0].VecEvalInt(b.ctx, input, buf); err != nil {
+		return err
+	}
+
+	result.ResizeFloat64(n, false)
+	i64s := buf.Int64s()
+	f64s := result.Float64s()
+	rander := rand.NewSource(time.Now().UnixNano())
+	randGen := rand.New(rander)
+	for i := 0; i < n; i++ {
+		if !buf.IsNull(i) {
+			randGen = rand.New(rand.NewSource(i64s[i]))
+		}
+		f64s[i] = randGen.Float64()
+	}
+	return nil
 }
 
 func (b *builtinCeilIntToDecSig) vectorized() bool {
diff --git a/expression/builtin_math_vec_test.go b/expression/builtin_math_vec_test.go
index 230372109d405..7f6e43833c529 100644
--- a/expression/builtin_math_vec_test.go
+++ b/expression/builtin_math_vec_test.go
@@ -110,6 +110,9 @@ var vecBuiltinMathCases = map[string][]vecExprBenchCase{
 		{retEvalType: types.ETInt, childrenTypes: []types.EvalType{types.ETInt, types.ETInt}, geners: []dataGenerator{nil, &rangeInt64Gener{-10, 10}}},
 		{retEvalType: types.ETInt, childrenTypes: []types.EvalType{types.ETInt, types.ETInt}, childrenFieldTypes: []*types.FieldType{{Tp: mysql.TypeInt24, Flag: mysql.UnsignedFlag}}, geners: []dataGenerator{nil, &rangeInt64Gener{-10, 10}}},
 	},
+	ast.Rand: {
+		{retEvalType: types.ETReal, childrenTypes: []types.EvalType{types.ETInt}, geners: []dataGenerator{&defaultGener{0, types.ETInt}}},
+	},
 	ast.CRC32: {
 		{retEvalType: types.ETInt, childrenTypes: []types.EvalType{types.ETString}},
 	},