Abstract: Random phasing is an effective measure for restricting the parasite lobes of phased array antenna employing digital phase shifter.However,the optimal results being a statistical average,the antenna pattern of random phasing is unsteady with the scanning angle and scanning period,so it is not easy to form the actually needed codes for control of the antenna scanning.In this paper,to restrict the parasite lobes and to form the beam scanning codes,the Genetic Algorithm(GA) is applied to optimize the random phase distribution,and results reveal that GA can obtain steady and optimal phase distribution for the phased array antenna.