diff --git a/time_test.go b/time_test.go
index a6935f3..133b1b5 100644
--- a/time_test.go
+++ b/time_test.go
@@ -219,7 +219,7 @@ func TestPrepareCron2(t *testing.T) {
 
 func TestRun(t *testing.T) {
 	now := time.Now().Add(time.Second * 2)
-	tmr := NewTimer(time.Now(), WithStaticDate(now), WithRunCountLimit(1))
+	tmr, _ := NewTimer(time.Now(), WithStaticDate(now), WithRunCountLimit(1))
 	c := make(chan int)
 	tmr.AddTask(func() {
 		fmt.Println("hello world")
@@ -241,7 +241,7 @@ func TestRun(t *testing.T) {
 
 func TestInvalid(t *testing.T) {
 	exp := `[{"repeat":[{"unit":3,"value":19},{"unit":2,"value":8},{"unit":1,"value":15},{"unit":0,"value":0}],"every":false}]`
-	tmr := NewTimer(time.Now())
+	tmr, _ := NewTimer(time.Now())
 	err := tmr.ImportRepeats(exp)
 	if err != nil {
 		t.Fatal(err)
@@ -268,7 +268,7 @@ func TestDate(t *testing.T) {
 		},
 		Every: false,
 	}
-	tmr := NewTimer(time.Now(), WithRepeats(&rp))
+	tmr, _ := NewTimer(time.Now(), WithRepeats(&rp))
 	tmr.AddTask(func() {
 		time.Sleep(time.Second * 2)
 		fmt.Println(tmr.NextTimer())
diff --git a/timer.go b/timer.go
index e34e8f3..fd016b1 100644
--- a/timer.go
+++ b/timer.go
@@ -4,12 +4,13 @@ import (
 	"context"
 	"encoding/json"
 	"errors"
+	"fmt"
 	"sort"
 	"sync"
 	"time"
 )
 
-func NewTimer(baseDate time.Time, opts ...TimerOptions) StarTimer {
+func NewTimer(baseDate time.Time, opts ...TimerOptions) (StarTimer, error) {
 	timer := StarTimer{
 		base:     baseDate,
 		nextDate: time.Time{},
@@ -57,6 +58,9 @@ func NewTimer(baseDate time.Time, opts ...TimerOptions) StarTimer {
 		}
 
 		if op.repeats != nil {
+			if err := timer.repeatsCheck(op.repeats); err != nil {
+				return timer, err
+			}
 			timer.repeat = append(timer.repeat, op.repeats)
 		}
 		if op.tasks != nil {
@@ -66,8 +70,43 @@ func NewTimer(baseDate time.Time, opts ...TimerOptions) StarTimer {
 			timer.runLimit = op.runLimit
 		}
 	}
-	return timer
+	return timer, nil
+}
+
+func (t *StarTimer) repeatsCheck(rp *Repeats) error {
+	if rp == nil {
+		return errors.New("nil point of Repeats")
+	}
+	if rp.Every {
+		return nil
+	}
+	for _, r := range rp.Repeat {
+		switch r.Unit {
+		case STAR_MINUTE, STAR_SECOND:
+			if r.Value > 60 || r.Value < 0 {
+				return fmt.Errorf("invalid value:%d", r.Value)
+			}
+		case STAR_HOUR:
+			if r.Value > 24 || r.Value < 0 {
+				return fmt.Errorf("invalid value:%d", r.Value)
+			}
+		case STAR_MONTH:
+			if r.Value > 12 || r.Value < 1 {
+				return fmt.Errorf("invalid value:%d", r.Value)
+			}
+		case STAR_DAY:
+			if r.Value > 31 || r.Value < 1 {
+				return fmt.Errorf("invalid value:%d", r.Value)
+			}
+		case STAR_WEEK:
+			if r.Value > 7 || r.Value < 0 {
+				return fmt.Errorf("invalid value:%d", r.Value)
+			}
+		}
+	}
+	return nil
 }
+
 func (t *StarTimer) IsRunning() bool {
 	t.mu.RLock()
 	defer t.mu.RUnlock()
@@ -105,7 +144,10 @@ func (t *StarTimer) Stop() error {
 }
 
 func (t *StarTimer) NextTimer() time.Time {
-	return t.parseNextDate(time.Now(), true)
+	if t.base.Before(time.Now()) {
+		return t.parseNextDate(time.Now(), true)
+	}
+	return t.parseNextDate(t.base, true)
 }
 
 func (t *StarTimer) NextTimerAfterDate(date time.Time) time.Time {
@@ -128,7 +170,7 @@ func (t *StarTimer) ImportRepeats(r string) error {
 	t.mu.Lock()
 	defer t.mu.Unlock()
 	if t.running {
-		return errors.New("coonot import repeats to already running timer")
+		return errors.New("cannot import repeats to already running timer")
 	}
 	var rep []Repeats
 	err := json.Unmarshal([]byte(r), &rep)
@@ -136,6 +178,11 @@ func (t *StarTimer) ImportRepeats(r string) error {
 		return err
 	}
 	t.repeat = make([]*Repeats, 0, len(rep))
+	for _, v := range rep {
+		if err = t.repeatsCheck(&v); err != nil {
+			return err
+		}
+	}
 	for _, v := range rep {
 		t.repeat = append(t.repeat, &v)
 	}
@@ -152,6 +199,11 @@ func (t *StarTimer) SetBaseDate(date time.Time) {
 func (t *StarTimer) ResetWithRepeat(base time.Time, repeat []*Repeats) error {
 	t.Stop()
 	t.base = base
+	for _, v := range repeat {
+		if err := t.repeatsCheck(v); err != nil {
+			return err
+		}
+	}
 	t.repeat = repeat
 	return t.Run()
 }
@@ -166,7 +218,16 @@ func (t *StarTimer) Run() error {
 	if t.running {
 		return nil
 	}
-	t.nextDate = t.parseNextDate(time.Now(), false)
+	for _, v := range t.repeat {
+		if err := t.repeatsCheck(v); err != nil {
+			return err
+		}
+	}
+	base := time.Now()
+	if t.base.After(base) {
+		base = t.base
+	}
+	t.nextDate = t.parseNextDate(base, false)
 	if t.nextDate.Before(time.Now()) {
 		return errors.New("Invalid Timer Options,Please Check")
 	}