Abstract: The three-dimensional imaging radar system based on thinned array is investigated to reduce the system complexity. The multiple phase center aperture synthesis method in time division mode is proposed to eliminate the high side lobes of thinned array. Combine with motion compensation, the synthesized phase center both in quantity and distribution are same as the full array. Using simulated annealing algorithm to optimize the location of antennas, so as to minimize the number of antennas used. For the array length of cross-track is far small than the scene width, the sub-aperture three-dimension imaging method is adopted. The simulation results denote the validity of the method proposed in the paper.