Abstract: Phased Array Antenna is an important EM Scattering source. on the stealth weapon platform. In this paper, phased array antenna mode scattering characteristics has been calculated. The RCS data has been used for microwave imaging by ISAR imaging method of rotating objects. General rules of phased array antenna scattering characteristics and scattering centers arrangement distribution chart have been studied. Tilting antenna and matched impedances can greatly reduce anten na mode RCS in the threaten area. The result is useful for phased array antenna mode RCS reduction.