Abstract: The problem of high velocity impedance has become one of the obstacles in the oil and gas exploration in south China.A special survey should be adopted for getting the seismic imaging beneath the high velocity basalt layer.In area ofthe high velocity impedeace,the reflection signals are weak,so that we obtain the seismic image hardly.It is very important to increase length of of set in the seismic data acquisition to get the deep seismic reflection.There are three methods for the wide angle seismic profiling to solve the high velocity impedance problem.The first is to delineate the structure of the top and bettom of the impedance layer and to obtain the velocity of the basement from the refraction seismic data.The second is to get rid of the noise near offset to improve the quality of the imageing using the wide reflection.The third is to get image for the low velocity layers below the high velocity impedance with converted wave in the high velocity layer.All of them can be combined by using various data to improve the quality of the imaging.Jiangling depression is one of the key prospecting areas in south China.The extensive distribution of basalt in this area deteriorates the seismic data seriously.The reflections are not clear,the S／N ratio is low,the event continuity is bad,and the multiples are strong.In order to get the clear structure,we increased the length of the offset.Unfortunately,more difficulty in seismic data processing appeared. Besides the complex seismic waves and signals,the most important problem is the obvious anisotropic characteristics alongside the length increasing.Much research work has been done about the time-distance curve of the seismic waves in the various media.Conventional NMO is not available to achieve seismic imaging of the long offset.The deep seismic imaging and the analysis of seismic amplitude characteristics can be achieved only based on the phase correction.A fourth order correction can be made by the three terms of Taylor serie given by Taner and Koehler.Using more than two terms of the Taylor series can improve velocity analysis and CMP stacking .However,a simple truncation generally causes a significant travel time error at very large offset-to-depth ratio.To have a travel time approximation with good accuracy at large offsets,a high order long offset NMO correction (LNMO) was used.