A planar dielectric lens is designed, and the performance is simulated with HFSS. The performances of plane layers dielectric lens antenna are analyzed when microstrip patch antenna is adopted as the feeding antenna. The influence of the distance from the lens to feeding antenna is discussed. The deviation from the central axis and the unparallel between the feeding antenna and the lens towards the lens antenna are investigated. A beam steerable plane dielectric lens antenna is achieved. The maximum gain of the lens antenna is about 17.43 dB which is about 9.07 higher than that of the patch antenna and the feeding antenna is allocated flexible.