The power is out of control near the fundamental voltage vector in the traditional direct power control system,which leads to high harmonic content in AC side. The influence of voltage vector to active power and reactive power is analyzed on the basis of the mathematical model of PWM rectifier power. A control strategy with dual switch table in the non-fixed sectors is presented in view of the unsteady power regulation under the traditional switch table. The method realizes the effective power regulation, and obtained the better dynamic control performance, the lower harmonic current. Finally Matlab / Simulink simulation results verify the correctness and practicability of the control strategy.