China's hydropower resources are mainly concentrated in west China, which is also the meizoseismal area of China. The seismic safety of high earth rockfill dams in these areas is one of the most prominent problems in China's hydropower development. Based on the relevant provisions of Code for seismic design of hydraulic structures of hydropower project (NB 35047-2015), the three-dimensional nonlinear seismic response analysis of Lianghekou super high core rockfill dam was carried out by using the ground motion time history generated by site related design response spectrum of the scenario earthquake. The research results showed that the dam acceleration amplification effect was very significant in the middle part of the valley which is above 4/5 dam height and within 1/3 dam axis length for Lianghekou super high core rockfill dam located in a V-shaped Valley. It showed obvious whiplash effect and three-dimensional valley effect. On this basis, the seismic reinforcement range of Lianghekou super high core rockfill dam was proposed.