Abstract: At present, seismic exploration is facing many challenges in the "double complex" area, especially the undulating surface make it difficult to accurately image the underground complex structures. In this paper, we have studied the elastic wave prestack reverse time migration method for undulating surface, and a simple and effective treatment method was adopted to solve the free boundary conditions of undulating surface. In addition, the storage strategy of the effective boundary was used to solve the problem of big storage of elastic wave prestack reverse time migration. The numerical experimental results also show that this method can accurately reconstruct the source wave field. Finally, test of SEG Canadian overthrust fault model for undulating surface has further verified the effectiveness of the method proposed in this paper.