A symmetrical drop in power grid voltage in the Z source wind power generation system will lead to an increase of the capacitor voltage of Z-source network as well as the occurrence of AC-side current, thus seriously threatening the safety of wind turbines and converters, and destroying the stable operation of the system. In view of the above-mentioned problems, a proposal has been made of a fault ride-through strategy for permanent magnet direct drive power generation system with Z source under symmetrical drop in voltage. A detailed analysis has been made of the working principle of Z source permanent magnet direct drive system, followed by the eatablishment of the mathematical model of Z source inverter. Under the normal voltage of the power grid, the dual closed loop control strategy of the Z source capacitor voltage outer loop control and the current loop control is used to realize the unit power factor of the Z source wind power generation system. In the case of the three-phase symmetry drop of the grid voltage, an analysis has been made of the power flow situation. The low voltage crossing of the system can be achieved with a parallel between the energy dissipation crowbar circuit and the input terminal of the Z source network, thus maintaining a constant Z source voltage and stable AC side current. Finally, a model is to be built in Matlab/Simulink to simulate the system, with its results verifying the effectiveness of the proposed method.