Abstract: As for water drive development in complex fault block oil reservoir,it is easy to form preferential seepage channels and result in water breakthrough in oil wells.The main means of identifying the preferential seepage channels are logging comparison,core analysis,pressure drop testing,and etc.,however,the well testing interpretation model for the preferential seepage channels identification cannot meet the present demands.Through the base form analysis of the preferential seepage channels,the well testing models for preferential seepage channels have been established.By finite difference method,the discrete solution of the models has been carried out and the bottom hole pressure and pressure derivative double logarithm curve of well test interpretation chart has been drawn.The well testing response of preferential seepage channels mainly has two flows,the radial flow and linear flow.Besides,the influence of channel permeability,the storage ratio and the width on the well testing response of preferential seepage channels has been analyzed.In the end by use of the double logarithm curve chart,the interpretation of pressure drop test data has been made and the curve fit effect is good.Therefore,this method can be used as identification method for preferential seepage channels and put into wide application.