Abstract: An improved gravitational search algorithm (IGSA) is proposed in the paper. By introducing the mutation operator of genetic algorithm, the local search capability of GSA is improved. Also the way to apply improved gravitational search algorithm to beam shaping for antenna array and premature convergence problem are well solved. Given the determinate number and space between the antenna array elements, the amplitude and phase of excitations are optimized and by this method to make the shaped-beam patterns meet the designing request. Simulation results prove the feasibility and efficiency of the proposed method.