Abstract:The principle of relative static correction using first arrival stack is as follows. The first arrival legs of common shot gathers or common receiver gathers are flat- tened using a proper velocity,then stacked to form their first arrival stack sections; when there is still static correction problem,first arrival legs are staggered (uncon- nected);the unconnected first arrival legs are then corrected to a smooth “tendency line”so as to find proper relative static corrections.This method is mainly used to calculate the residual static corrections which are bigger than half period and can not be obtained by using conventional static correction methods.Real data processing shows that this method is an effectual one for improving the seismic sections within a surface complicated area.