Abstract: Aiming at the problem of target effect in sidelobe canceller,polarization filtering technique based on oblique projection operator is introduced into sidelobe cancellation system,and a new method to eliminate target effect is presented.This new method  estimates jamming signal polarization parameters,and calculates oblique projection operator;The calculated oblique projection operator acts on accessory channel echo,as a result,the jamming signal  extracted from the echo and target signal is entirely rejected.Compared with normal polarization filtering methods,this new method can reject target signal entirely and improve cancellation ratio greatly, only  jamming signalJP2 polarization parameters needed.Theory analysis and computer simulation  prove the validity of this method.