The invention relates to a device for charging an accumulator by using wind power in bicycle running and an application method. The device is characterized in that the accumulator and a driving device are mounted on a rear frame of a bicycle, wherein the driving device comprises an impeller, a speed increaser and a generator. The application method comprises the following steps: in the bicycle running period, the impeller on the rear frame of the bicycle is driven by wind to rotate; the speed increaser is driven to accelerate the rotating speed of the impeller; the output end of the speed increaser drives the generator to rotate for generating electricity; and the electricity generated by the generator charges the accumulator through a lead. The beneficial effect of the device is that the bicycle can be used for inputting kinetic energy to the accumulator in places without power supply.