Abstract：Instead of using normal elevation datum correction,the wave equation datum correction has been used in a condition of dramatic surface elevation variation and of that surface-consistent hypothesis is untenable.Aimed at condition of rugged surface often appeared in a field,the paper uses"add-up step by step"for wavefield continuation in an operation of wavefield extrapolation,which realized wave equation datum correction with finite-difference based on nonflat surface.Because of using finite-difference extrapolator with improving optimized coeffidents,the algorithm improved computational efficiency on a basis of ensuring computational accuracy.While eliminating accurately long-wavelength statics,the short－wavelength statics have been also eliminated in a certain level.The method got ideal results both in synthetic data and in real test data,which provides useful way for using finite-difference operation to realize prestack wave equation datum correction based on non-flat surface and finally the prestack wave equation depth migration.
