Based on the grid voltage vector orientation (VOC), considering the similarity of PWM rectifier circuit structure and the structure of AC motors, this paper uses AC motors similar flux observation method, constructs virtual grid flux vector control as directed, and establishes a common virtual grid magnetic chain orientation (VFOC) of double-loop vector control system. Compared with the traditional VOC program, VFOC program can save AC grid voltage sensor, which can both save space and reduce costs. In order to solve the effect of the deviation of initial value on the control effect in the virtual grid flux observation process, it proposes an anti-windup initial value observation approach, which can effectively solve the error of the virtual grid flux observer due to initial value. Experimental verification using VFOC can achieve unity power factor PWM rectifier control, and the controller has better static stability and dynamic speediness.