The electrical vehicle (EV) charging/swapping stations are fundamental facilities for the development of EVs, this paper introduces a systematic approach for the cost benefit analysis (CBA) of the EV charging/swapping station. It starts from the scale of the stations, with restriction of reasonable allowable time from customers. The critical part of the station is described by queuing model, the parameters of the queuing models are calculated by considering the EVs' driving characteristics, the parameters of different types of EVs and the reasonable waiting time for charging/swapping. By connecting all the cost and benefit with common parameters, the number of charging piles, swapping piles and swapping batteries, the approach offers a practical solution for the planning of the station size, and the solution balances the requirements between the customers and economic efficiency.