Abstract: With the boundary of paleo-structural map of sedimentary sequence in fluid migration period,systematically taking into consideration the coefficients(such as reservoir thickness,porosity,perme-ability and pressure,etc.) pertained to fluid migration within sedimentary sequence,based on the division of migration-accumulation units,abiding the regularity that fluid migrates from higher potential area to the lower one,using the modeling software of Petro Charge to model the trace of fluid migration,the fluid-containing ability of lithologic traps on slopes in oil-and-gas bearing basins is finally evaluated.The applications in the Qianjiang Sag of the Jianghan Basin and the Shengbei Sag of the Tuha Basin show that,fluid potential analysis is an effective ancillary approach in oil-and-gas bearing evaluation of litho-logic traps.