Android is becoming more and more popular. Up to the first half of 2012, the Android phone market share has reached 52.5%. Only consider smart phone, the ratio is even more than 75%. Contacts is very important to users. Contacts synchronization system allows the user contacts can be stored on a network server. Users can process their data via multiple clients. And server can ensure consistency and security of users' data. Therefore, based on SyncML protocol we designed and implemented a contacts synchronization system for Android. Existing Android contacts sync software generally use separate synchronization protocol. They export all the contacts data into a file, and apply rsnyc algorithm to find the changes. In contrast, we provider a new way to find changes and use the SyncML to implemente the sync system.