The lithological migration and preserved-amplitude migration problem of fault block reservoirs is rather rough in the delicate exploration of China’s oil field. In this paper, we implement the prestack least square reverse time migration based on plane-wave encoding to solve these problems with an improvement of efficiency. The imaging test of plane-wave LSRTM algorithm and its comparison with RTM and poststack LSRTM verify that the prestack LSRTM has the advantages including: (1) resolution enhancement and amplitude compensation in mid-deep part with the increase of iterations which can be compared to LSRTM (2) high computational efficiency to be practical (3) stable convergence even when the velocity model is complex.