The crowbar protection circuit can be greatly improved the low-voltage ride-through (LVRT) capability of the doubly-fed wind power system.This paper established the mathematical model of doubly-fed induction generator (DFIG), the model is to the key parameters of the Crowbar protection circuit based on IGBT type --Optimal discharge enable resistance value range studied.And through MATLAB / Simulink to build a model of VSCF DFIG wind power generation system. The simulation show that the necessity to take crowbar protection circuit when the grid voltage drop significantly.