NOVELTY - Apparatus for anaerobic fermentation of agricultural organic waste and for recovering agricultural biogas comprises acid fermentation reactor (1), phase reactor (9), where fermentation reactor is connected by pipeline to continuous stirring kettle reactor, where reactor has filter device and filter device has conical shell, inner cavity, where inner part of shell has filter material and top of shell has an opening or seal cover plate, and lower end has feeding port (2) and discharging port (3) in horizontal position. The feeding port is lower than discharge port of fermentation reactor.    USE - As apparatus for anaerobic fermentation of agricultural organic waste and for recovering agricultural biogas (claimed); for livestock and poultry cultivation.    ADVANTAGE - The apparatus improves agricultural organic waste degradation efficiency of fermentation systems, equipment and piping; relieves blockage of bottlenecks; reduces fluctuation interference of anaerobic fermentation system in low temperature environment; and improves stability and increases speed of operation of biogas production rate.    DETAILED DESCRIPTION - An apparatus for anaerobic fermentation of agricultural organic waste and for recovering agricultural biogas comprises an acid fermentation reactor (1), a phase reactor (9), where the acid fermentation reactor is connected through a pipeline to a continuous stirring kettle reactor, where the reactor has a filter device, and the filter device comprises a conical shell, inner cavity, where inner part of shell has filter material and top of the shell has an opening or a seal cover plate, and lower end has a feeding port (2) and a discharging port (3) in horizontal position. The feeding port is lower than the discharge port of acid fermentation reactor. An INDEPENDENT CLAIM is included for a method of recovering agricultural biogas using the apparatus involving: preprocessing raw material, adding 8% to 12% oxygen of total solid matter concentration in vacuum in the acid fermentation reactor, inoculating the reactor to biogas digesters, stirring for 2 hours 5 minutes, maintaining at 37 degrees C, subjecting to anaerobic fermentation in fermentation liquid in reactor at initial pH of 7.0-7.2, maintaining constant pH of 6.5, and adding fermentation product in acetic acid, where raw material is livestock excrement or livestock and poultry excrement and the mixture of crop straw, holding raw material in total C:N ratio of 20-30:1 to form acid-producing fermentation product; feeding the product to filter in filter device, adjusting filter device feeding port height, separating solid-liquid, degrading straw residue and solid, keeping more than a part of filtrate in filter device, taking volatile organic acid with a short chain small molecule organic substance liquid, entering liquid into filter material in filter device, continuously feeding filtered liquid through pump in oxygen free environment into phase reactor, taking anaerobic sludge from beer or municipal sewage treatment plant UASB reactor, where reflux ratio of phase control reactor is 2:1, diluting water and increasing flowing speed in the reactor inner part, maintaining sludge and maintaining anaerobic reaction continuous operation at 32 to 35 degrees C, discharging and collecting in gas collecting bottle.    DESCRIPTION OF DRAWING(S) - The figure shows schematic diagram of apparatus for anaerobic fermentation of agricultural organic waste and for recovering agricultural biogas.    Acid fermentation reactor (1)    Feeding port (2)    Discharge port (3)    Discharge hole (4)    Stirrer blade (5)    Sampling port (6)    Gas collecting bottle (7)    Gas flow meter (8)    Phase reactor (9)    Reaction area (10)    Feeding opening (12)    Discharging hole (14)    Three phase separator (21)    Water outlet pipe (22)    Filter device (23)