In order to improve the precision of high-speed impact simulation for projectile penetration， the depth of penetration（DOP） process of sapphire is simulated by finite element method and smooth particle hydrodynamics（FEM-SPH） adaptive coupled model. The accuracy is verified by DOP experiment. The calculation results of the traditional FEM model and the FEM-SPH fixed coupled model are compared. The results show that the FEM-SPH adaptive coupled model has obvious advantages in calculation accuracy.