A system model of the threephase voltage source pulsewidth modulation rectifier (VSR) under threephase static coordinate axis was proposed, and the mathematical model under the rotating dq coordinate axis was derived. Then, the feedforward decoupling control method was introduced to control the threephase VSR system. Next, the VSR designing technology, such as proportionalintegral (PI) controller design, main circuit design and key parameter setting, was discussed in detail. Finally, a design instance of VSR was presented, and its simulation model was established with Matlab/Simulink simulation platform. By showing good performance of the VSR, the simulation results prove that the VSR system model, the control scheme and the design method are correct and effective.