In installing antenna arrays of wireless communication systems, communication arrays are often optimized so that the side-lobe level is minimized. The goal is to reduce influences of interferences. Because building antenna arrays is difficult and expensive, optimization design by computer simulation in advance is required. In this paper, we utilized the particle swarm optimization to optimize of antenna arrays. The side-lobe level of an antenna array is minimized by adjusting positions and exciting weights of array elements under the constraint of certain beam-width limitation. The results show that techniques of particle swarm optimization can efficiently achieve optimize of antenna arrays.