The structure and the control measure of the fast battery swapping system for electric vehicles are described.The hardware structure of the multi-robot collaborative battery swapping system is designed，which consists of multiple Cartesian-coordinate robots with six-degree-of-freedom and multi-sensors，battery tank stackers with three-degree-of-freedom，transit stations，and battery charging racks.The main control unit of the battery swapping system is also designed，and the working flow for the system is proposed，which guarantees a fast and full-automatic operation for the battery swapping.The methods proposed have found application in charging and swapping substations in Shandong Province.