Abstract: The work flow and key technology of wide area real-time differential GPS prototype system are introduced. Based on nearly 50 IGS global Stations' real-time observation data at 1 second interval,real-time satellite clock offset is continuously calculated second by second. On the mean time,real-time orbit corrections and clock corrections to Broadcast Ephemeris are calculated and sent to users by wireless communication network. The users with double frequency receiver can calculate the real-time position by the RT-PPP (Real-time Precise point positioning) methods. Initial results of tests show real-time clock corrections' accuracy is better than 0.2 ns; real-time positioning RMS are better than 10 cm and 20 cm in the horizontal and vertical direction,respectively.