The invention relates to a testing system of a vehicle control unit of a pure electric sedan. The testing system comprises a vehicle-mounted computer and the vehicle control unit, wherein the vehicle-mounted computer system is installed with CANoe test system software; an outer case of the vehicle-mounted computer is provided with a CANcardXL interface; the CANoe test system software is communicated with the vehicle control unit through a CAN (Controller Area Network) 1 and a CAN 2 respectively; the CANoe test system software is connected with an IO8444 interface cable through the CANcardXL interface; and the IO8444 interface cable is connected with the vehicle control unit. The testing system has the beneficial effects that a testing system is quickly established by using the CANoe test system software and the corresponding interface cable, so that testing content of the vehicle control unit is finished with the least time, and meanwhile, the testing system can also be used as an auxiliary testing means for software-in-loop testing and hardware-in-loop testing, so that an automatic detection technology is realized and the testing period is shortened.