Abstract: With the development of technology in oil and gas exploration and production,the complex structure imaging and deeper structure imaging become more and more important in seismic exploration.Post-stack time migration can not solve the problem of imaging of complex structure because of the limitation of the method itself.Pre-stack migration technique is one of the most effective methods to solve the meticulous velocity analysis and complex structure imaging.It is also a development tendency of seismic data imaging,and it is the key technique that can resolve the complex structure imaging in areas where lateral velocity varies violently.By the case from western edge of Ordos Basin,this paper gives the method of complex structure imaging,the steps of realization and the result of imaging.The result of research indicates that the pre-stack depth migration has greater dominant position than post-stack migration in describing the complex structure.