In allusion to the application of LCL filter in three-phase voltage rectifier circuit, this paper will apply LCL filter to battery energy storage system, compared with traditional single LC filter, we can use smaller inductance value to achieve better filtering effect, eliminating the problems caused by conventional filters, such as large volume, high cost, poor dynamic response of system. According to the requirements of the design of the whole system, by analyzing the circuit principle and control strategy of the system, using the three-phase voltage type PWM rectifier (VSR) and bidirectional DC/DC converter, through a simple design method of the parameters of the LCL filter, ultimately, the correctness of the theoretical analysis is verified by simulation and experiment and realize the constant power charging and discharging of the battery.