We have established a five-segment fault model based on field investigation and the linear noncoherent characteristics of InSAR wrapped deformation. The five-segment fault model is consistent with the surface rupture trace of field investigation at most of the segments. Then we use this fault model as constraints to simulate the co-seismic deformation of Wenchuan earthquake derived from InSAR technology. Our favored fault model contains five segments with varied dips, based on the seismogenic structure of precise aftershock relocation. The simulated deformation by forward modeling matches very well the InSAR data with a RMS of 0.3~0.35 m. The inverted slip distribution is concentrated in the depth of 0～20 km and the maximum slip is 10m. Among the largest-slip areas Beichuan area has relatively more concentrated slip at shallower depth than other areas. This may be the deep cause why Beichuan area is the most severely destroyed area in this earthquake. The inverted rake distribution shows that there is a transition along the direction of SW-NE. It is mainly reverse and some right-lateral slip at Wenchuan and Beichuan areas, but it is dominantly right-lateral with some thrusting in Qingchuan area, with the mean rake of 97° and 138° respectively. The inverted seismic moment M₀ is 7.7×10²⁰ N·m, and the moment magnitude M_w is 7.9.