The invention relates to the field of a fermentation technology, in particular to a straw fermentation device, the straw fermentation device comprises a box body, a moving device is fixed on an outerbottom surface of the box body, a first partition plate is vertically welded inside the box body, the box body is divided into a processing chamber and a tool storage chamber by the first partition plate, the processing chamber is vertically welded with a second partition, the second partition plate is perpendicular to the first partition plate, the second partition plate divides the processing chamber into a heating chamber and a humidifying chamber, and the heating chamber is fixedly provided with a heating mechanism. The straw is added into a fermentation tank through a feeding port, underan action of the first suction fan, the hot air heated in the heating chamber is added to the humidifying chamber for humidifying to increase the humidity of the hot air, under the action of a secondsuction fan, the humidified hot air is introduced to the fermentation tank, and under the action of a stirring mechanism, the temperature and humidity of the straw in the fermentation tank are increased to accelerate the fermentation of the straw.