Abstract: The muhipath effect is an avoidless problem which the tracking radar and the searching radar among CIWS has to face. This paper analyses the form of the muhipath effect on geometry, emphasizes the distance difference between the direct wave and the reflected wave, according to this inherent characteristic, the paper introduces the theory of HRR to the design of radars among CIWS, discusses the spike pulse technology and ultra wide band technology which often be used, finally proposes the method of time-frequency code to obtain the high range resolution and avoid the muhipath effect.