Abstract:The stack can improve signal-to-noise ratio of seismic section,but hypothetical condition is that the traces on the gather stack in phase after NMO.The phase of seismic wavelet is not simply quantitative add but vectorial add on stack section,so not only must make correction for amplitude and time on all seismic traces but also for phase before stack in order to that amplitude,time and phase of all seismic traces on a gather remain consistency before stack.Only doing so can get best stacking results.According to surface-consistent hypothesis and through iterative calculation between shot set and receiver set,the optimal phase correcting factor can be determined which realized phase correction.After surface-consistent phase correction,the seismic waveform can be aligned and phase can be consistence in maximum possibility on CMP gather and optimal stack section can be made after stack.We use variable phase correction to realize phase correction.The real data test showed the corredness of the method.