Abstract: In seismic numerical simulation, the boundary reflection generated by the finite calculation area will interfere with the results of normal wave field simulation. In this paper, the artificial boundary condition is introduced to reduce the influence of boundary reflection. For the decoupled and uncoupled differential forms of PML (perfectly matched layer) boundary conditions, different spatial difference orders are used for seismic wave field numerical simulation. When the order of spatial difference is increased, the nondecoupled PML differential form has more advantages in computational efficiency and implementation mode than those of the decoupled. Aiming at the problems of CE (ClaytonEngquist) boundary condition limited by the incident angle of incident wave, low accuracy at the boundary, and poor absorption effect, the secondorder CE boundary condition and PML boundary condition are combined into a new combined boundary condition, which can reduce the thickness of attenuation band while ensuring the absorption effect, so as to improve the calculation efficiency. The effectiveness of this algorithm is verified by the numerical simulation results.

Key words: numerical simulation, finite difference, perfectly matched layer method, combination boundary condition ,