Using the GPS velocity data of 27 stations around the East Kunlun Fault as restraints, the authors first inversed the slip rates of the eastern Kunlun Fault, the northern margin fault of Qaidam Basin, the Mani-Yushu Fault and the Maergaichaka Fault before the MS 8.1 west Kunlun Mountains Pass earthquake with 3-D elastic half-space dislocation model. Based on the tectonically meaningful data of the background deformation field, the authors calculated the strain field and seismic moment accumulation rate field. The results show that there are two obvious regions of high moment accumulation rates, one is just in the Xidatan-Dongdatan segment of East Kunlun Fault where the MS 8.1 earthquake happened in 2001.