The M_S 8.0 Wenchuan earthquake and its 2216 aftershocks were relocated using the double difference algorithm.The horizontal and vertical errors of the 2061 relocated hypocenters are approximately 1～2km and 2～3km,respectively.The epicenter of main shock is approximately 31.00°N,103.38°E,the focal depth is about 13km and the seismogenic structure is the central fault of Longmenshan Fault zone.The total length of spatial distribution of aftershocks along the strike of the fault is about 330km and the predominance distribution of focal depth is 3～20km,which shows obviously the characteristic of segmented activity.The seismicity of the southern part mainly concentrates on the central fault of Longmenshan Fault zone,and some earthquakes occurred on the range-front and range-back faults;the dip of the three faults seems to become gentler gradually from west to east,forming imbricate ruptures.The central fault and Pingwu-Qingchuan Fault of the Longmenshan Fault zone are involved in the seismogenic process,and the seismic rupture is both of thrust napping and right-lateral strike-slipping.