Abstract:Studying seismic wave propagating rule and seismic response in complex medium needs carrying out numeric simulation of elastic wave equation under tiny grid separation,which brings an issue of giant computational works,and using grid-various computation is effective way to reduce computational works.The paper gives a method for implementing grid-various finite-difference computation: the computation in tiny grid is used in local complex medium area,the computation in gross grid is carried out in rest area.In transitional area between two grids,the transitional link is finished by changing differential operator and wavefield interpolation.The theoretical analysis and numeric simulation showed that it does not affect the simulation of seismic wave propagation in the transitional area between the gross and tiny grid,which attained the goal both reducing computational works and guaranteeing the precision.