Abstract: Taking the three-phase matrix isolation rectifier(3MIR) as the research object, in order to reduce the current distortion rate at the grid side, maintain the constant output voltage and speed up the dynamic response speed of the system, the traditional model predictive control strategy is improved, and a model predictive current control strategy based on the optimal modulation ratio is proposed. Firstly, the network side current is predicted by 3MIR discrete mathematical model, and the evaluation function is constructed with the minimum network side current error as the control objective. Secondly, in order to fix the switching frequency and reduce the amount of calculation, the optimal modulation ratio corresponding to the minimum current error is derived by the evaluation function, and the pulse signal is generated combined with the bipolar current space vector modulation strategy to drive the power switch. Finally, the proposed model predictive control is compared with the traditional double closed-loop PI control and the traditional model predictive control. The simulation results verify the feasibility and effectiveness of the proposed control strategy.