This paper designs an Android communication system on the basis of studying the related communication research, and the system utilizes the wifi network and point-to-point architecture and messages between client sides are delivered by means of the Socket. In addition to the instant text information transmission, functions of on-line and off-line as well as file transfer are added. The adoption of the multi-threading technology enhances the program's utilization of the system resources. Better operating results are obtained in the test on the Android platform.