When the grid voltage drops, the stator and rotor of the wind turbine generate impulse voltage and impulse current, which will affect the security of the grid. In order to realize the low voltage ride-through of the brushless doubly-fed wind turbine and ensure the uninterrupted operation of the wind turbine under the grid voltage drop, transient analysis of the stator voltage and current of the brushless doubly-fed generator under the grid voltage drop is conducted. A mathematical model of brushless doubly-fed generator in the static coordinate system of power winding is built, then the dynamic change process of its power winding flux linkage and control winding voltage at the moment of grid voltage drop is deduced and analyzed, moreover a control strategy combining integral sliding mode direct power control and fault ride through control is proposed, hence the low-voltage ride through control of brushless doubly-fed generator is completed. The control strategy combined with the fault ride-through control completes the low voltage ride-through control of the brushless doubly-fed generator. Through MATLAB/Simulink and the semi-physical simulation experiment platform, the simulation and experimental results prove the correctness of the deduced power winding flux and control winding voltage dynamic change process and the effectiveness of the control strategy. The control strategy effectively inhibits the voltage and current distortion of the stator control winding side and improves the low voltage crossing performance of the brushless doubly-fed generator.