Three-phase current source PWM rectifier (CSR) is a nonlinear object with multi variable and strong coupling, so it is difficult to control the complex object. Three-phase CSR is usually used by the direct current control mode of dual-stage loop control structure, but there are some problems in the common direct current control method. In this paper, the discrete state feedback decoupling controller is used to control the object, which can solve the control problem. The mathematical model of three-phase CSR and the principle of direct current control are analyzed, the discrete-state feedback decoupling control method is discussed, the simulation model of the control method is established. The simulation results verify the advantages of the proposed method, and the control effect of the proposed method is better than that of the traditional PID control method.