Abstract：Coseismic gravity change and deformation in layer viscoelastic medium caused by Yushu Ms7.1 were calculated using PSGRN/PSCMP based on different fault slip models.The results show that:1）Coseismic gravity change and displacement calculated for teleseimic waveform based on the fault slip model are more consistent with results from field survey；2）Coseismic gravity change only locates near by faults，and the range influenced by coseismic horizon displacements are obvious widely than that by coseimic gravity change；3）The obsolute gravity change during the period of two years before the earthquake and one month after the earthquake is obvious different from the result calculated，which indicats that observed obsolute gravity change implies earthquake preparation and coseismic change and postseismic change.
