According to the actual demand of unexpensive and portable devices for inland navigation, the paper designed and implemented a mobile AIS data display system based on android platform. The system can connect to ship carried AIS devices by Bluetooth, and enable an intelligent mobile device (phone or tablet) to receive and decode AIS data to obtain realtime information of vessels around and paint them onto electronic nautical charts. With the functions of vessel dynamic monitoring and vessel information querying, the system can act as a simple portable navigator for the ship handlers of small inland vessels by running it in their mobile devices