In recent years, intelligent vehicles have become one of the major research topics of vehicle engineering and a new opportunity for automotive industry. Simulation and experiment are essential for the development of intelligent vehicle technologies. Vehicle positioning system such as GPS, plays an important role on intelligent vehicle, the GPS model has important significance in the development of intelligent vehicle simulation system. Primarily focusing on application requirements of intelligent vehicle simulation platform for GPS sensor model, considering the main factors affecting the positioning accuracy in vehicle driving environment, this paper establishes a new GPS model using software based on physical and functional characteristics of GPS. As the basis of this model system, a precise ephemeris model is established to obtain the coordinates of GPS satellites at any time. A new occlusion model is proposed in order to describe the external environmental disturbance more effectively, this model takes into account not only the emission angle of the satellite signal and the shadow of the earth but also the scene in the model such as buildings, trees and other shelter. By using the Doppler effect and solving the pseudo range equation, velocity and position are calculated. And in the process of measurement, the pseudo range error and the frequency shift error are taken into account. As part of the positioning system, the positioning process of the differential mode is established in this paper. The GPS model has higher fitting precision and the performance of the entire system is verified through comparing with the measurement data from real sensor.