In this paper, synthesis of unequally spaced linear antenna arrays based on an Inheritance Learning Particle Swarm Optimization (ILPSO) is presented. In order to improve the optimization efficiency of the PSO algorithm, the authors propose an inheritance learning strategy that can be applied to different topology of different PSO algorithms. In ILPSO algorithm, each cycle contains several PSO optimization processes, and uniform initial particle positions, part of which inherited from the good results in pre-cycles, are adopted in post-cycles.