A large number of nonlinear components are used in the AC microgrid of photovoltaic grid-connected system which is equipped with a certain capacity of energy storage devices. When there is a large number of nonlinear loads in the microgrid system, the current waveform of the microgrid system is prone to distortion, resulting in harmonic pollution. In order to reduce the interference of grid-connected microgrid system on the receiving grid, based on the LCL grid-connected inverter structure, PI + repeated control compound control strategy was adopted to realize the tracking and control of command current on the basis of meeting the tracking speed and accuracy, which can effectively suppress harmonic current and compensate reactive power. Based on the composite control, it is considered that when the photovoltaic output power and load power change, the multi-function grid-connected inverter under the composite control can still realize dual functions when the researched microgrid and the grid transmit different power in different modes. Finally, the simulation results show that the strategy realizes harmonic compensation and reactive power compensation, and transmits power to the grid at the same time.