For the problem of the pattern synthesis for planar array with large elements spacing, a planar array pattern synthesis method of wideband real time delay based on particle swarm optimization algorithm was proposed. In this method, according to the characteristics of the main lobe orientation and the grating lobes orientation under the condition of real time delay, the wideband real time delay was adopted to suppress the grating lobe of pattern. Then, the structure of array was optimized by particle swarm optimization algorithm and the pattern with higher main-side-ratio was obtained. The effectiveness of the proposed method was indicated by the simulation for 8×8 rectangular planar array. Furthermore, the relationship between the grating lobe suppression performance and the signal bandwidth was studied through the simulation.