diff --git a/README.md b/README.md
index 315f2df5..7a1cddb4 100644
--- a/README.md
+++ b/README.md
@@ -153,6 +153,8 @@ QQ交流群：[288600953](https://jq.qq.com/?_wv=1027&k=5QGgCDe)
 
 
 ## 更新日志 
+**2.5.0：** 
+- 优化：修复ArrayList在多线程中addItem出现的角标越界问题
 
 **2.4.9：** 
 - 重要：升级到gradle:3.4.2，低版本studio可能因为该项升级而产生错误，建议升级studio或手动修改classpath 'com.android.tools.build:gradle:3.4.2'到你的可用版本
diff --git a/demo/release/demo-release.apk b/demo/release/demo-release.apk
index c6798d5f..404b37bc 100644
Binary files a/demo/release/demo-release.apk and b/demo/release/demo-release.apk differ
diff --git a/easyPhotos/src/main/java/com/huantansheng/easyphotos/models/album/AlbumModel.java b/easyPhotos/src/main/java/com/huantansheng/easyphotos/models/album/AlbumModel.java
index 780c1f01..2588175f 100644
--- a/easyPhotos/src/main/java/com/huantansheng/easyphotos/models/album/AlbumModel.java
+++ b/easyPhotos/src/main/java/com/huantansheng/easyphotos/models/album/AlbumModel.java
@@ -18,7 +18,7 @@
 import com.huantansheng.easyphotos.utils.String.StringUtils;
 
 import java.io.File;
-import java.util.ArrayList;
+import java.util.List;
 
 /**
  * 专辑模型
@@ -227,7 +227,7 @@ public String getAllAlbumName(Context context) {
      *
      * @return 当前专辑项目的图片集
      */
-    public ArrayList<Photo> getCurrAlbumItemPhotos(int currAlbumItemIndex) {
+    public List<Photo> getCurrAlbumItemPhotos(int currAlbumItemIndex) {
         return album.getAlbumItem(currAlbumItemIndex).photos;
     }
 
@@ -236,7 +236,7 @@ public ArrayList<Photo> getCurrAlbumItemPhotos(int currAlbumItemIndex) {
      *
      * @return 专辑项目集
      */
-    public ArrayList<AlbumItem> getAlbumItems() {
+    public List<AlbumItem> getAlbumItems() {
         return album.albumItems;
     }
 
diff --git a/easyPhotos/src/main/java/com/huantansheng/easyphotos/models/album/entity/Album.java b/easyPhotos/src/main/java/com/huantansheng/easyphotos/models/album/entity/Album.java
index b11b9887..8e07c5cc 100644
--- a/easyPhotos/src/main/java/com/huantansheng/easyphotos/models/album/entity/Album.java
+++ b/easyPhotos/src/main/java/com/huantansheng/easyphotos/models/album/entity/Album.java
@@ -1,7 +1,9 @@
 package com.huantansheng.easyphotos.models.album.entity;
 
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.LinkedHashMap;
+import java.util.List;
 
 /**
  * 专辑模型实体类
@@ -9,17 +11,23 @@
  */
 
 public class Album {
-    public ArrayList<AlbumItem> albumItems;
+    final public List<AlbumItem> albumItems;
     private LinkedHashMap<String, AlbumItem> hasAlbumItems;//用于记录专辑项目
 
     public Album() {
-        albumItems = new ArrayList<>();
+        albumItems = Collections.synchronizedList(new ArrayList<AlbumItem>());
         hasAlbumItems = new LinkedHashMap<>();
     }
 
     private void addAlbumItem(AlbumItem albumItem) {
-        this.hasAlbumItems.put(albumItem.name, albumItem);
-        this.albumItems.add(albumItem);
+        synchronized (albumItems) {
+            boolean absent = !albumItems.contains(albumItem);
+            if (absent) {
+                this.albumItems.add(albumItem);
+                this.hasAlbumItems.put(albumItem.name, albumItem);
+            }
+        }
+
     }
 
     public void addAlbumItem(String name, String folderPath, String coverImagePath) {
diff --git a/easyPhotos/src/main/java/com/huantansheng/easyphotos/models/album/entity/AlbumItem.java b/easyPhotos/src/main/java/com/huantansheng/easyphotos/models/album/entity/AlbumItem.java
index 997d4d80..36faf4b5 100644
--- a/easyPhotos/src/main/java/com/huantansheng/easyphotos/models/album/entity/AlbumItem.java
+++ b/easyPhotos/src/main/java/com/huantansheng/easyphotos/models/album/entity/AlbumItem.java
@@ -1,6 +1,8 @@
 package com.huantansheng.easyphotos.models.album.entity;
 
 import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
 
 /**
  * 专辑项目实体类
@@ -11,17 +13,22 @@ public class AlbumItem {
     public String name;
     public String folderPath;
     public String coverImagePath;
-    public ArrayList<Photo> photos;
+    public final List<Photo> photos;
 
     AlbumItem(String name, String folderPath, String coverImagePath) {
         this.name = name;
         this.folderPath = folderPath;
         this.coverImagePath = coverImagePath;
-        this.photos = new ArrayList<>();
+        this.photos = Collections.synchronizedList(new ArrayList<Photo>());
     }
 
     public void addImageItem(Photo imageItem) {
-        this.photos.add(imageItem);
+        synchronized (photos) {
+            boolean absent = !photos.contains(imageItem);
+            if (absent) {
+                this.photos.add(imageItem);
+            }
+        }
     }
 
     public void addImageItem(int index, Photo imageItem) {