This paper proposes an improved power-flow control method for the voltage-source-inverter grid-tied system. Comparing with the traditional grid-tied droop control, it can realize accurate power-flow control and restrain the harmonic current injected to grid. This method is designed based on the classical power-flow phasor model, and consists of an improved droop control in grid-tied mode and a harmonic-compensation control loop. Subsequently, mathematical modeling, analysis and contrast experiment results of the traditional method and the proposed method are presented, which validate the excellent performance of the proposed method.