diff --git a/node/cron/cron.go b/node/cron/cron.go
index 184ceeb..2174bb0 100644
--- a/node/cron/cron.go
+++ b/node/cron/cron.go
@@ -16,6 +16,7 @@ import (
 // be inspected while running.
 type Cron struct {
 	entries  []*Entry
+	indexes  map[string]int
 	stop     chan struct{}
 	add      chan *Entry
 	snapshot chan []*Entry
@@ -85,6 +86,7 @@ func New() *Cron {
 func NewWithLocation(location *time.Location) *Cron {
 	return &Cron{
 		entries:  nil,
+		indexes:  make(map[string]int),
 		add:      make(chan *Entry),
 		stop:     make(chan struct{}),
 		snapshot: make(chan []*Entry),
@@ -125,7 +127,11 @@ func (c *Cron) Schedule(schedule Schedule, cmd Job) {
 		Job:      cmd,
 	}
 	if !c.running {
-		c.entries = append(c.entries, entry)
+		if index, ok := c.indexes[entry.ID]; ok {
+			c.entries[index] = entry
+			return
+		}
+		c.entries, c.indexes[entry.ID] = append(c.entries, entry), len(c.entries)
 		return
 	}
 
@@ -168,6 +174,13 @@ func (c *Cron) runWithRecovery(j Job) {
 	j.Run()
 }
 
+// Rebuild the indexes
+func (c *Cron) reIndex() {
+	for i, count := 0, len(c.entries); i < count; i++ {
+		c.indexes[c.entries[i].ID] = i
+	}
+}
+
 // Run the scheduler.. this is private just due to the need to synchronize
 // access to the 'running' state variable.
 func (c *Cron) run() {
@@ -181,6 +194,7 @@ func (c *Cron) run() {
 	for {
 		// Determine the next entry to run.
 		sort.Sort(byTime(c.entries))
+		c.reIndex()
 
 		var effective time.Time
 		if len(c.entries) == 0 || c.entries[0].Next.IsZero() {
@@ -207,7 +221,11 @@ func (c *Cron) run() {
 			continue
 
 		case newEntry := <-c.add:
-			c.entries = append(c.entries, newEntry)
+			if index, ok := c.indexes[newEntry.ID]; ok {
+				c.entries[index] = newEntry
+			} else {
+				c.entries, c.indexes[newEntry.ID] = append(c.entries, newEntry), len(c.entries)
+			}
 			newEntry.Next = newEntry.Schedule.Next(time.Now().In(c.location))
 
 		case <-c.snapshot:
diff --git a/node/node.go b/node/node.go
index 9e45f25..a0af0e0 100644
--- a/node/node.go
+++ b/node/node.go
@@ -140,7 +140,7 @@ func (n *Node) keepAlive() {
 	}
 }
 
-// 启动服务
+// 停止服务
 func (n *Node) Stop(i interface{}) {
 	close(n.done)
 	n.Node.Del()