Based on the analysis of the direct current power supply mode with deficiency ,a power supply mode of threephase PWM rectifierparallelPWM inverter is proposed. The DC voltage of threephase PWM rectifier contains harmonics that cause the DC side voltage ripple changing constantly. When the AC power supply is connected in parallel with three phase PWM rectifier, the effect of voltage fluctuation must be considered. To solve this problem by increasing the resistance on the rectifier output side to inhibit the voltage ripple effects on the stability of parallel system .And the influence of parallel module accessing time on the parallel process is analyzed. This paper proposes a control method which can realize the free distribution of a single module output power. Finally, the feasibility of the control method is verified by simulation.