Using the PSGRN/PSCMP software and the fault model offered by USGS and on the basis of finite rectangular dislocation theory and the local layered wave velocity structures of the crust-upper-mantle, the influences of crustal layering and thickness on co-seismic gravity changes and deformation of Wenchuan earthquake have been simulated. The results indicate that: the influences have a relationship with the attitude of faults and the relative position between calculated points and fault. The difference distribution form of simulated results between the two models is similar to that of co-seismic effect. For the per centum distribution, it’s restricted by the zero line of the co-seismic effects obviously. Its positive is far away from the zero line. For the crustal thickness, the effect is about 10%-20%. The negative and the effect over 30% focus around the zero line. The average influences of crustal layering and thickness for the E-W displacement, N-S displacement, vertical displacement and gravity changes are 18.4%,18.0%,15.8% and 16.2% respectively,When the crustal thickness is 40 km, they are 4.6%,5.3%,3.8% and 3.8%. Then the crustal thickness is 70 km, the average influences are 3.5%, 4.6%,3.0% and 2.5% respectively. Using the PSGRN / PSCMP software and the fault model offered by the USGS and on the basis of finite rectangular dislocation theory and the local layered wave velocity structures of the crust-upper-mantle, the influences of crustal layering and thickness on co-seismic gravity changes The deformation of Wenchuan earthquake has been simulated. The results indicate that: the influences have a relationship with the attitude of faults and the relative position between calculated points and fault. The difference distribution form of simulated results between the two models is similar to that of For the per centum distribution, it’s restricted by the zero line of the co-seismic effects obviously. Its positive is far away from the zero line. For the per centum distribution, the effect is about 10% -20%. The negative and the effect over 30% focus around the zero line. The average influences of crustal layering and thickness for the EW displacement, NS displacement, vertical displacement and the gravity changes are 18.4%, 18.0%, 15.8% and 16.2% respectively when the crustal thickness is 40 km, they are 4.6%, 5.3%, 3.8% and 3.8%. are 3.5%, 4.6%, 3.0% and 2.5% respectively.