In view of power coupling problems of the traditional grid inverter current vector PI control, it needs complex decoupling control, and one of the difficult is to achieve grid inverter system with no steady state error control. In order to solve this problem, this paper takes the instantaneous power outer ring and the inner ring of the inductance current dead-beat control strategy, and derives the discrete mathematical model of three-phase grid inverter, reduces a lot of coordinate transformation, and the design of the grid inverter control system was simplified. With the results of Matlab simulation show that the change of grid current, the control strategy can still achieve grid inverter output active and reactive power decoupling, and grid inverter output current has a good dynamic tracking performances, the low of current harmonic content satisfies the requirement of grid.