In order to relieve the pressure of grid which was caused by massive unguided charging behavior of electric vehicles,at the same time,maintained the safe and stable operation of the power grid,this paper presents a charging optimization strategy for electric vehicles．The main idea of this strategy is to make charging plan through time-of-use electricity price,thus,the electric vehicle can be moved to normal period and valley period for charging．The objective function of the algorithm is to minimize the charging cost and the peak-valley difference,based on this system,the paper builds a mathematic model of multi-objective optimization,and artificial fish swarm algorithm is used to solve the model．Finally,a distribution network is used as an example to carry out simulation analysis．This simulation results verify the effectiveness of the algorithm,and with the increase of electric vehicles’ penetration rate,the effect of the algorithm is more significant,which means that the algorithm will also have strong adaptability in the scenario that the number of electric vehicles will increase in the future.