Analyzing the dynamic variation of crust horizontal deformation nearby the Longmenshan Fault before Lushan M7.0 earthquake,we proposed that Wenchuan M8.0 earthquake play an active role for Lushan M7.0 earthquake.There exited obvious earthquake preparation background of crustal horizontal deformation in medium-and long-term before Lushan M7.0 earthquake.Using finite-fault plane solution of Lushan M7.0 earthquake,we calculated the surface coseismal displacement field of Lushan M7.0 earthquake by spherical dislocation model.Contrasted with the processing result of high frequency observation data of GPS reference station SCTQ near the epicenter,we concluded that the coseismal influence scope of Lushan M7.0 earthquake is small.