NOVELTY - Zero slag discharging biogas fermentation device comprises an acidification reaction pool, a gas pool, a clear water tank. The acidification reaction pool provided with sawtooth grill, where inner space of acidification reaction pool is divided into upper raw material chamber and lower juice outlet chamber. The juice outlet chamber is provided with outer connected discharging pipe. The gas pool upper part is gas storage chamber, lower part is fermentation chamber. The top is provided with air storage chamber and connected to the airway.    USE - The zero slag discharging biogas fermentation device is useful for producing biogas (claimed).    ADVANTAGE - The device: is simple; has rich source of raw materials, high rate of conversion rate, high and stable gas production.    DETAILED DESCRIPTION - Zero slag discharging biogas fermentation device comprises an acidification reaction pool, a gas pool, a clear water tank. The acidification reaction pool provided with sawtooth grill, where inner space of acidification reaction pool is divided into upper raw material chamber and lower juice outlet chamber. The juice outlet chamber is provided with outer connected discharging pipe. The gas pool upper part is gas storage chamber, lower part is fermentation chamber. The top is provided with air storage chamber and connected to the airway. The gas pool upper part is set with juice storage chamber. The juice storage chamber and gas pool fermentation chamber are connected through juice outlet pipe. The outlet pipe one end extends to bottom center of gas pool fermentation chamber, where other end is connected to juice storage chamber. The gas pool side is set with a clean water tank. The clean water tank and juice storage chamber are connected through filter pipe. An INDEPENDENT CLAIM is also included for producing bio gas, comprising continuously adding raw material according to C/N ratio of 20-30:1 into acidification pool for hydrolysis reaction, producing acid, where raw material comprises crop straw, weed leaves, human and animal excreta, household organic garbage, other added with clay or sludge raw material of weight 1-2%, acidification reaction pool produces organic acid liquid, by juice outlet pipe into inlet of gas pool anaerobic fermentation pool, producing methane gas into gas storage chamber, organic acid liquid produced in acidification reaction pool by gas anaerobic fermentation pool, methane gas is produced by gasguide tube airway output.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic representation of the zero slag discharging biogas fermentation device.