This paper proposes a simplified model of PWM converter, which is proved to be effective in saving simulation time. Take doubly-fed wind power system as an example, the PWM converter is simplified in two aspects: a) the AC side of converter precisely and flows the output voltage reference; b) ignore the power loss of converter, which means the AC side power equals to DC side. Based on the two assumptions, the voltage of AC side could be replaced by a voltage-controlled voltage source, and the DC side could be replaced a controlled current source. By this way, the complex IGBTs converter is simplified to an equivalent circuit. Simulation with specific model and simplified model then performed in PSCAD/EMTDC. By comparing their waveforms and simulation speed, the correctness and benefits of the proposed model are verified.