The positioning system based on GPS was presented in this paper. As the core of SCM C8051F021 and LEA-5H, the system sends the navigation data of the GPS receiver to the microcontroller. And then, through the RS232 serial port send the processed data to PC for the solution. After the coordinate transformation and many other treatments, display the target track in real-time on the host computer programmed by VB. Field test results show that the system can correctly and reliably measure the attitude and position information of moving vehicle in realtime, it has important value for many practical applications.