The embodiment of the invention discloses a system for improving wind turbine generator low voltage ride through characteristics and a method. The system comprises a three-phase dynamic voltage compensator, a saturated core-type reactor and a DC energy storage device, wherein the three-phase voltage compensator comprises three groups of inverter voltage lines, and the inverter voltage lines are mutually independent and not coupled mutually; the input ends of the inverter voltage lines are electrically connected with the DC energy storage device; the output ends of the inverter voltage lines are electrically connected with the saturated core-type reactor and the wind turbine generator respectively; the DC energy storage device is electrically connected with the saturated core-type reactor; and the saturated core-type reactor is connected with a power grid. When power grid voltage fluctuates in a small range, the three-phase voltage compensator carries out dynamic compensation on voltage at two ends of the wind turbine generator. When short circuit fault happens to the power grid, the saturated core has the maximal impedance, and the low voltage ride through characteristics of the wind turbine generator are improved.