Due to the fact that in the traditional grid-connected current control method of single proportional integrating (PI) and repeat control (RC) strategies, a distortion problem can be found in the photovoltaic inverter output current, which fails to ensure the stability of the system, and result in a poor power quality of the grid-connected current under the control system of high-order LCL type photovoltaic inverter. In view of this problem, a compound optimal control strategy of PI+ repetitive control has thus been proposed under two-phase static coordinate system. Firstly, in the existing PI+ repetitive control strategy, the introduction of weighting coefficient m to the PI controller branch helps to improve the regulation function of PI link, thus accelerating the response speed of the system to meet the dynamic performance of the system. Secondly, by introducing the weighting coefficient n into the branch of repetitive controller, the steady-state error of the system can be continuously corrected and eliminated, so as to meet the steady-state requirements of the system. Finally, the effectiveness of theoretical analysis and strategy optimization can be verified by simulation experiments. The simulation results show that the optimization scheme simplifies the coordinate transformation and decoupling calculation, improves the harmonic suppression ability of the photovoltaic inverter output, and reduces the total harmonic distortion rate of the grid connected current of the inverter.