In low voltage micro grid , three-phase photovoltaic (pv) grid power generation system as the object, the mathematical model of three-phase photovoltaic (pv) grid inverter is analyzed. Grid inverter current inner ring use the instantaneous current control which can realize the current dynamic tracing system, but the current inner ring user the traditional PI control to power feed-forward decoupling effect and complex rotating coordinate transformation. On the basis of the instantaneous current control, in this paper, the three-phase photovoltaic (pv) grid inverter is proposed a outer ring for the instantaneous power control, the inner ring for instantaneous current control strategy of proportion of quasi resonant. Through the simulation analysis, instantaneous active reactive power control loop reference for photovoltaic (pv) grid inverter power control; In photovoltaic (pv) grid power system output power under the condition of mutations, current inner loop control is fast accurate dynamic tracking performance, and realize the decoupling control of power, output power, high quality for power grid simulation results validate the control strategy of effective effect.