Abstract: Proposes an improved PSO（Particle Swarm Optimizer） called BDPSO（Behavior of Distance PSO） that particles do different behavior due to different regions of the swarm.In the attraction region particles speed up fly to the best position of the swarm and in the repulsion region they fly at normal speed.Some benchmark problems are tested for the performance of BDPSO and results show that BDPSO performances better than PSO both on convergence rate and accurate solutions.