NOVELTY - Aquatic plant and poultry excrement light-dark stepped coupled biological hydrogen production device, comprises a dark fermentation hydrogen production jar and a light fermentation hydrogen production reactor comprising light fermentation hydrogen production jar and pipe-type light fermentation hydrogen production reactor. The dark fermentation hydrogen production jar is provided with a biological gas outlet I and a material outlet I, and feed inlet and liquid outlet are arranged at middle. A heating cover I is arranged out of dark fermentation hydrogen production jar body.    USE - Used as a aquatic plant and poultry excrement light-dark stepped coupled biological hydrogen production device.    ADVANTAGE - The device improves the yield of hydrogen production by using organic waste.    DETAILED DESCRIPTION - Aquatic plant and poultry excrement light-dark stepped coupled biological hydrogen production device, comprises a dark fermentation hydrogen production jar and a light fermentation hydrogen production reactor comprising a light fermentation hydrogen production jar and a pipe-type light fermentation hydrogen production reactor. The top of dark fermentation hydrogen production jar is provided with a biological gas outlet I, the bottom is provided with a material outlet I, and a feed inlet and a liquid outlet are arranged at the middle part. A heating cover I, which controls the fermentation temperature, is arranged out of the body of dark fermentation hydrogen production jar. A stirrer and a three-phase separator are arranged in the jar. The body of the light fermentation hydrogen production jar is made by organic glass. A heating cover I, which controls the fermentation temperature, is arranged out of the body of light fermentation hydrogen production jar. A water distributor is arranged on the light fermentation hydrogen production jar. A biological gas outlet II is arranged above the water distributor. The middle part of the light fermentation hydrogen production jar is provided with a liquid inlet, the bottom is provided with a material outlet II, which is connected with the material inlet of the pipe-type light reactor through a circulation pump. The outlet of the pipe-type light reactor is connected with the inlet of the light fermentation hydrogen production jar. The liquid outlet of the dark fermentation hydrogen production jar is connected with the liquid inlet of the light fermentation hydrogen production jar. The biological gas outlet I and II are connected to a hydrogen storage jar. The pipe-type reactor is constructed by a transparent pipe fixed on a support. The support is provided with a yellow light source to provide illumination. An INDEPENDENT CLAIM is also included for a light-dark coupled anaerobic fermentation hydrogen preparation method by aquatic plant and poultry excrement, comprising performing ultrasonic-acidification complex treatment of aquatic plant and poultry excrement, mixing them in a ratio of (2:1)-(10:1), adding into a dark fermentation hydrogen production jar, then adding activated sludge (pH 5-7), which is dried and pre-processed by microwave as a bacterial source, where the mass ratio of inoculated bacterial source is 15-30%, passing nitrogen to remove air in the hydrogen production device, where the mass ratio of inoculated photosynthetic bacteria is 5-15%, the pH value of the fermentation broth is 7-8, using yellow light to provide illumination, and performing light fermentation at 30-45?oC to produce hydrogen.