The characteristic of the “magnetization grating” is analyzed for the first time,which is obtained by periodically changing the magnetization of the magnetized film.The coupling relation and the phase of guided optical waves(GOWs) are investigated by use of the coupledmode theory in the magnetization grating.Our calculation indicates that,the mode conversion efficiency(MCE) is sensitive to the grating period;the phase of the mode conversion(MC) lights is a periodic function of the coupling coefficient,and the π phase shift will be achieved by adjusting the magnetization.Consequently,the magnetization grating is potentially applied to the sensor,the optical switch,and the BPSK communication system.