Aim at planar array radar, this paper investigated an approach which only applies one kind of analog weighting at element level to suppress sidelobes of sum and difference beam simultaneously. Consequently, sum and difference channels were constructed, and the analog weights were determined by making optimal adaptive filtering for the supposed interferences within the sidelobe area. In order to improve sidelobe suppression effect, digital weighting at subarray level was adopted, which was used to approximate the patterns obtained by the Taylor or Bayliss weight. The proposed approach reduces the hardware cost and complexity. Simulation results demonstrate its validity.