Abstract：The main factors which influence the absorbing effects of the perfectly matched layer (PML) method are the thickness of absorbing layer and the attenuation coefficient. Based on the numerical simulation of the seismic wave field, the author discusses the impact of the thickness of absorption layer and the attenuation coefficient on the absorption effect. The results show that, under the condition of constant attenuation coefficient, the larger the thickness of the absorption layer is, the weaker the boundary reflection becomes. The absorption layer thickness of 12~20 traces is fairly appropriate. When the thickness of the absorption layer is smaller, the boundary reflection gets more and more weaker or even becomes zero with increasing attenuation coefficient. Nevertheless, if the attenuation coefficient is further enlarged, the boundary reflection will gradually appear again. Therefore, we must pay attention to the choice of attenuation coefficient in practice. The attenuation coefficient is generally between 500 and 2000. If the attenuation coefficient is larger than 3000, the absorption effect is not satisfactory.
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