Abstract:The paper analyzed NMO stack in a situation of variation in surface altitude and in near-surface velocity in seismic data processing at mountain area and its relation with statics,proposed a processing scheme based on smoothing surface.Through decomposition of NMO formina into two half-hyperbola and in a condition of using same T0 velocity,the NMO correction related to shot-altitude and receiver-altitude is done separately and then basic moveout correction is done before stack.The results showed that the method achieved useful experience.and good effects in seismic data processing at typical mountain area.