Particle swarm optimizer (PSO) is a new evolutionary computation method, which has been successfully applied to many fields. Through mechanism analysis of the standard particle swarm optimizer, a linear equivalent representation of the velocity update equation is given. Thus a new particle swarm optimizer-nonlinear particle swarm optimizer (NPSO) is described in this paper. It can dynamically adjust the limit position that distribute within the ellipse located by the best positions of the population and itself, and drop out of the local minimum point. The simulation results show the correctness and efficiency of the presented methods.