The invention discloses a dynamic matching method improving the wind power generation efficiency under a medium and low air speed. The dynamic matching method includes the steps that dynamic matchingparameters under the medium and low air speed are obtained and stored in a controller of a wind power generation system; the air speed is measured in real time, and the real-time air speed is obtained; the magnitude of the real-time air speed and the preset dynamic matching air speed is judged, and a judgment result is obtained; the air speed is measured in real time again according to the judgment result, or a nominal air speed differed from the real-time air speed by a first set threshold value is obtained from the controller, and dynamic matching parameters of the nominal air speed are obtained; the energy storage speed increasing state of a wind turbine is achieved according to the dynamic matching parameters; when the rotating speed of the wind turbine is increased to the sum of the changing amount of the wind turbine rotating speed under the maximum power output and the wind turbine rotating speed, the wind turbine is converted to be in an energy-releasing power generation state;and when the rotating speed of the wind turbine is reduced to the wind turbine rotating speed under the maximum power output, dynamic matching is over. By means of the above method, the wind power generation efficiency under the medium and low air speed can be improved.