Based on the fluid calculation FLUENT software, surge changes within the reservoir area and its propagation along the reservoir bank, caused by possible instability of the landslide-induced deformation body in the reservoir area of a hydropower station, have been simulated. Some impacts of the water retaining structure upon surge propagation along the reservoir bank are taken into consideration and analyzed, and the initial swell height, and the maximum wave height along the opposite bank, the reservoir bank and the dam site are obtained by calculation analysis, and compared with the calculated results given by PAN Jia-zheng method. Analysis results show that the numerical simulation can well reflect the wave run-up process over the bank slope and wave propagation along the reservoir banks, and the interaction by the wavy water surface and the surge superposition in the reservoir area is actually simulated. Due to barrier effect given by the dam structure, a higher swell is formed by repeated water surface oscillation with the surge superposition in the reservoir area. Thus the calculated initial swell and the maximum surge height within the reservoir area well conform to the actual situation, which can provide references for the engineering design and surge disaster prevention of the reservoir area close to the dam site.