According to the surface rupture belts, deformation characteristics, kinematic characteristics and aftershock migration characteristics formed by Wenchuan M_S8.0 earthquake along the Yingxiu-Nanba segment of Central Fault Belt on May 12^th 2008, the research result shows:(1) From Yingxiu to Nanba, the faulting mode changes from reverse-thrusting to reverse-thrusting with right lateral slipping of comparable amplitude, and is accompanied by a weak rotation between the two walls of the fault; (2) On the whole the NE striking fault is dominated by thrusting with right lateral slipping, while locally there is NW striking thrusting with left lateral slipping; (3) The relation between earthquake cracks and the rupture surface, and the deformation characteristics of the overlapping shortening on the earth′s surface reveal that the rupture and strain energy release resulted from the combined action of regional tectonic stress in near E-W direction and local tectonic stress in NE direction. Based on the attitude change of surface cracks along the fault, we deduce that the direction of principal stress changes from SEE in Yingxiu to NEE in Nanba, which accords with the focal mechanism solutions of the mainshock and aftershocks determined with the CAP (Cut and Pasate) method.