Abstract: We use disturbance abnormity with features of precursor wave from pointing-precursor observation of epicenter area and nearby within hundreds kilometers in Qinghai-Sichuan area before the Wenchuan Ms 8.0 earthquake on May 12,2008 to search possible epicenter-source area.According to its abnormity vector,extent,time,space-location and the distribution characteristics of tectonic fracture,aided by construction of source-spreading function and inversion of quasi-Newton least square method.Computed epicenter-source is located on the northern segment of Longmenshan fracture,about 134 km away from real epicenter,occurred nearly 13 hours before this earthquake.