The utility model discloses a low-voltage ride through and reactive power control system for an asynchronous wind turbine generator set. The low-voltage ride through and reactive power control system comprises a generator set, a rectifier, an inverter, a converter controller, an energy storage capacitor, an unloading circuit and a transformer. The system has the following beneficial effects: voltage at a stator end of a generator is quickly supported when voltage of a power grid drops down so that the generator has a low-voltage ride through function and can supply certain reactive power to the power grid during low-voltage ride through; during normal operation of the power grid, the problem that a mouse-cage type asynchronous generator has to absorb a large amount of reactive power from the power grid to realize grid-connected operation is solved without reactive power compensation equipment; and furthermore, the asynchronous wind turbine generator set can emit or absorb certain reactive power and flexibly participate in reactive power adjustment of the system.