The eastern flank of Beidagang structure is one of main targets for exploration. It is important to predict the pressure of oil reservoir for oil & gas exploration and development. After researches the undercompacted shale zone, draws its profile map to show the distribution of undercompacted shale in vertical direction, this paper predicts the pressure in well, and makes the isomap of main production formation pressure, then analyzes the distribution law of pressure in horizon and realizes the relations between abnormal pressure and reservoir. The conclusion ofthis paper is proved by drilling well that the method of pressure prediction is valid and the pressure data of prediction is trusty.