Abstract: A modified particle swarm optimization algorithm is proposed and used to implement the element amplitude symmetry optimization with respect to the pattern synthesis of wide null of cylindrical array. The method uses cubic cyclical inertia weight change strategy, and reassigns the value of the particle through monitoring the value of fitness in real time. Thus it greatly improves the speed of convergence and effectively avoids converging to the local optimum. Simulation results show that the pattern of cylindrical array can achieve multiple wide null under the given condition and the number of iterations is decreased obviously, which proves the correctness and validity of the proposed algorithm.