diff --git a/rand/rand.go b/rand/rand.go
new file mode 100644
index 0000000..a05da8e
--- /dev/null
+++ b/rand/rand.go
@@ -0,0 +1,131 @@
+package rand
+
+import (
+	"crypto/rand"
+	"io"
+	"sync"
+	"time"
+
+	mrnd "math/rand"
+
+	"github.com/charlienet/go-mixed/bytesconv"
+)
+
+const (
+	uppercase = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+	lowercase = "abcdefghijklmnopqrstuvwxyz"
+	digit     = "0123456789"
+	nomix     = "BCDFGHJKMPQRTVWXY2346789"
+	letter    = uppercase + lowercase
+	allChars  = uppercase + lowercase + digit
+	hex       = digit + "ABCDEF"
+	_         = allChars + "/+"
+)
+
+type charScope struct {
+	bytes   []byte
+	length  int
+	max     int
+	bits    int
+	mask    int
+	lenFunc func(int) int
+}
+
+func StringScope(str string) *charScope {
+	return strScope(str, nil)
+}
+
+func strScope(str string, f func(int) int) *charScope {
+	len := len(str)
+
+	scope := &charScope{
+		bytes:   bytesconv.StringToBytes(str),
+		length:  len,
+		lenFunc: f,
+		bits:    1,
+	}
+
+	for scope.mask < len {
+		scope.bits++
+		scope.mask = 1<<scope.bits - 1
+	}
+
+	scope.max = scope.mask / scope.bits
+
+	return scope
+}
+
+var (
+	Uppercase = StringScope(uppercase)                          // 大写字母
+	Lowercase = StringScope(lowercase)                          // 小写字母
+	Digit     = StringScope(digit)                              // 数字
+	Nomix     = StringScope(nomix)                              // 不混淆字符
+	Letter    = StringScope(letter)                             // 字母
+	Hex       = strScope(hex, func(n int) int { return n * 2 }) // 十六进制字符
+	AllChars  = StringScope(allChars)                           // 所有字符
+)
+
+var randSource mrnd.Source = mrnd.NewSource(time.Now().UnixNano())
+var randLock sync.Mutex
+
+// 生成指定长度的随机字符串
+func (scope *charScope) RandString(length int) string {
+	n := length
+	if scope.lenFunc != nil {
+		n = scope.lenFunc(n)
+	}
+
+	ret := make([]byte, n)
+	for i, cache, remain := n-1, randInt63(), scope.max; i >= 0; {
+		if remain == 0 {
+			cache, remain = randInt63(), scope.max
+		}
+
+		if idx := int(cache & int64(scope.mask)); idx < scope.length {
+			ret[i] = scope.bytes[idx]
+			i--
+		}
+
+		cache >>= int64(scope.bits)
+		remain--
+	}
+
+	return bytesconv.BytesToString(ret)
+}
+
+// 获取指定范围内的随机数
+func RandInt(min, max int) int {
+	n := randNumber2(max - min)
+	return n + min
+}
+
+// 生成指定范围的随机数
+func RandInt32(min, max int32) int32 {
+	return int32(RandInt(int(min), int(max)))
+}
+
+func RandBytes(len int) ([]byte, error) {
+	r := make([]byte, len)
+	_, err := io.ReadFull(rand.Reader, r)
+	return r, err
+}
+
+// func randNumber(max int64) (int64, error) {
+// 	r, err := rand.Int(rand.Reader, big.NewInt(max+1))
+// 	return r.Int64(), err
+// }
+
+func randInt63() int64 {
+	var v int64
+
+	randLock.Lock()
+	v = randSource.Int63()
+	randLock.Unlock()
+
+	return v
+}
+
+func randNumber2(max int) int {
+	rnd := mrnd.New(randSource)
+	return rnd.Intn(max)
+}
diff --git a/rand/rand_test.go b/rand/rand_test.go
new file mode 100644
index 0000000..91bd3d3
--- /dev/null
+++ b/rand/rand_test.go
@@ -0,0 +1,118 @@
+package rand_test
+
+import (
+	"bytes"
+	"testing"
+	"time"
+
+	mrnd "math/rand"
+
+	"github.com/charlienet/go-mixed/rand"
+)
+
+func TestRandString(t *testing.T) {
+	t.Log(rand.AllChars.RandString(20))
+
+	// b, err := rand.RandBytes(32)
+	// t.Log(err)
+	// t.Log(hex.EncodeToString(b))
+}
+
+func TestRandHex(t *testing.T) {
+	h := rand.Hex.RandString(8)
+	t.Log(h)
+}
+
+func TestRandMax(t *testing.T) {
+	mrnd.Seed(time.Now().UnixNano())
+}
+
+func BenchmarkParallel(b *testing.B) {
+	rand.Hex.RandString(16)
+
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			rand.Hex.RandString(16)
+		}
+	})
+}
+
+func BenchmarkNoop(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		rand.AllChars.RandString(16)
+	}
+}
+
+func BenchmarkRandString(b *testing.B) {
+
+	for i := 0; i < 10; i++ {
+		rand.Hex.RandString(10)
+	}
+
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		rand.Hex.RandString(20)
+	}
+
+	// b.Run("randString", func(b *testing.B) {
+
+	// 	for i := 0; i < b.N; i++ {
+	// 		rand.Hex.RandString(256)
+	// 	}
+	// })
+
+	// for i := 0; i < b.N; i++ {
+	// 	rand.RandBytes(16)
+	// }
+}
+
+func BenchmarkString(b *testing.B) {
+	elems := []byte("abcdefghijk")
+
+	b.Run("1", func(b *testing.B) {
+		a := []byte{}
+		for i := 0; i < b.N; i++ {
+			for _, elem := range elems {
+				a = append(a, elem)
+			}
+		}
+	})
+
+	b.Run("2", func(b *testing.B) {
+		a := make([]byte, len(elems))
+		for i := 0; i < b.N; i++ {
+			for _, elem := range elems {
+				a = append(a, elem)
+			}
+		}
+	})
+
+	b.Run("3", func(b *testing.B) {
+		a := make([]byte, len(elems))
+		for i := 0; i < b.N; i++ {
+			a = append(a, elems...)
+		}
+	})
+}
+
+func BenchmarkConcatString(b *testing.B) {
+	elems := []string{"1", "2", "3", "4", "5"}
+
+	b.Run("add", func(b *testing.B) {
+		for i := 0; i < b.N; i++ {
+			ret := ""
+			for _, elem := range elems {
+				ret += elem
+			}
+		}
+	})
+
+	b.Run("buffer", func(b *testing.B) {
+		for i := 0; i < b.N; i++ {
+			var buf bytes.Buffer
+			for _, elem := range elems {
+				buf.WriteString(elem)
+			}
+		}
+	})
+}