Abstract: Grid-connected inverter is the core of direct current (DC) and alternating current (AC) conversion, and its performance is directly related to the efficiency of grid-connected photovoltaic and the power quality of the power system. However, during the long-term service of the inverter, the instability factors such as DC voltage fluctuation and power grid disturbance put forward higher requirements for the control strategy of the inverter. The voltage and current closed-loop control mechanism and its equivalent model of three-phase inverter were analysed systematically, and the strong robust closed-loop control strategy was proposed by combining the proportional-integral-derivative (PID) controller and feedforward control idea. At the same time, based on the equivalent model and power consumption, the design of inductance and capacitance in the filter circuit was improved. Finally, a complete simulation circuit model was built by using MATLAB Simulink software, and the performance of closed-loop control circuit and the filtering effect of filter were analysed comprehensively. Results show that, the disturbance removal time of the control strategy does not exceed 0.02 s, and it has good synchronization between output voltage and current. The harmonic distortion rate of the output voltage and current of the inverter is less than 1%, and the power quality of the three-phase voltage and current is good.