When the radar seeker is overlooking and detecting the ultra low altitude target, the tracking accuracy is significantly reduced because of multipath effect. When the line-of-sight angle is restricted near the Brewster angle, it can effectively reduce the multipath interference. Based on the principle of sliding mode control, an improved terminal guidance law of adaptive double sliding mode surface is designed. This guidance law can make the line-of-sight angle restricted near the Brewster angle, which can minimize the influence of multipath effects on the tracking precision. For the chattering problem of sliding mode control, the high gain continuous function is used instead of sign function, which greatly improves the interception performance of the ultra-low altitude target.