The invention discloses a human body leg movement energy collection system and a collection method. The human body leg movement energy collection system comprises a human body leg movement energy collection device, an electric energy management module and an energy storage module, wherein the human body leg movement energy collection device comprises an outer shell, a generator and a potentiometer are fixed on the outer shell, a working gear is fixed on a rotor of the generator, the bottom of the inner side of the outer shell is rotatably connected with a first rotary shaft, an oscillating bar and a sector gear are fixed on the first rotary shaft, the free end of the oscillating bar is located on the outer side of the outer shell, the sector gear is located on the inner side of the outer shell, an angle slider of the potentiometer is fixedly connected with the oscillating bar, and a gear box used for accelerating is arranged between the sector gear and the working gear. The human body leg movement energy collection device collects movement energy selectively; the energy is collected in a stage that a shank falls; if not being collected, the energy can be wasted; during electric energy collection, additional working of a human body is not needed, and the comfort of the human body is improved; the human body leg movement energy collection device is relatively compact in overall structure and relatively long in service life.