Convenience and safety of electric vehicle is essential for electric vehicle industrialization. Since electric vehicle charging load is of random and aggregation, different charging position and power affect power system in different way. Integration of EV charging load will become one of the important problems for grid plan. Based on current charging modes, this paper investigates the voltage distribution and power loss of power system with random distribution and local concentration of charging load taken into account. The simulation indicates that the voltage and power loss are both closely related with the distribution of charging load. The EV charging station design and site selection principle are proposed.