Aiming at the remaining oil distribution feature in ultrahigh water cut stage and oil layers depositional features in the north of Saertu Oilfield, guided by the hydrodynamic principle, based on the practical experience and analysis of cyclic water flooding in combination with numerical simulation, cyclic water flooding and various parameters are optimized, and layered cross injection with changing fluid direction is adopted so as to improve the development effect which has acquired favorable result in practice.