The construction and operation of electric vehicle (EV) charging station is the basic project in the EV industry development. This paper presents a dynamic optimizing method to improve the load characteristics of the distribution system based on the particle swarm optimization (PSO) algorithm. The optimizing strategy is operated by minimizing the load variance for a period as objective function, and the scale of charging station and the demands of customers as constraints. The customers’ travel performance is simulated by the stochastic method of probability distribution. And load characteristics of coordinated and uncoordinated charging are compared in different permeability. The conclusion shows that the dynamic optimizing strategy takes effect in mitigating load variance, optimizing distribution system characteristics and shifting peak load.