A new reflector shaping technique to improve the beam scanning capability of hybrid antennas (i.e. a reflector system illuminated by a phased array) is presented. Errors between the desired scan directions and the outgoing rays' directions in the scanning range are minimized by adjusting the reflector shape. This technique can be used to decrease the active element number of the feed array during the antenna scans, or reduce the gain loss caused by beam scanning when the number of active elements is given. An offset reflector antenna system is designed and analyzed, through which the validity of the technique given in this paper is demonstrated.