Detecting target echo in the exis-tence of self-screen jamming is a challenging work for radar system, especially when digital radio frequency memory (DRFM) technique is employed that mixes the jamming and tar-get echo both in spatial and time-frequency domain. The conventional way to solve this problem would suffer from performance deg-radation when physical target (PT) and false target (FT) are superposed in time. In this paper, we propose a new spatial filter accord-ing to the different correlation characteristic between PT and FT. The filter takes the ratio of expected signal power to expected jamming and noise power as the objective function un-der the constant filter modulus constraint. The optimal filter coefficients are derived with a generalized rayleigh quotient approach. More-over, we analytically compute the target detec-tion probability and demonstrate the applica-bility of the proposed method to the correla-tion coefficient. Monte Carlo simulations are provided to corroborate the proposed studies. Furthermore, the proposed method has simple architecture and low computation complexity, making it easily applied in mod radar sys-tem.