NOVELTY - A reverse flushing biological film filter carrier anaerobic purification tank comprises feed pipe (2), feed tank (1), filter plate (6) which is disposed in top block, reverse flushing pipe (4), sponges (3) which are evenly distributed in filter plate and are provided with sand (5), liquid groove having marsh gas collection film (8) and liquid storage pond which is outwardly extended in fluid reservoir and set with liquid outlet pipe, marsh gas collection film which is surrounded by marsh gas collection film rods, marsh gas pipe (10), liquid storage tank (12), and ditch spacer blocks (14).    USE - A reverse flushing biological film filter carrier anaerobic purification tank (claimed).    ADVANTAGE - The treatment method has high low organic content liquid feed degradation efficiency, discharge liquid meets required standards, gas production rate is greatly improved, and reverse flushing step does not produce clogging.    DETAILED DESCRIPTION - A reverse flushing biological film filter carrier anaerobic purification tank comprises feed pipe, feed tank which set in between filter plate and top block having feed pipe and reverse flushing pipe, filter plate which is disposed in top block, reverse flushing pipe, sponges which are evenly distributed in filter plate and are provided with sand, liquid groove having marsh gas collection film and liquid storage pond which is outwardly extended in fluid reservoir and set with liquid outlet through fine sand, liquid outlet pipe, marsh gas collection film which is surrounded by marsh gas collection film rods, marsh gas pipe, liquid storage tank, and ditch spacer blocks. An INDEPENDENT CLAIM is included for reverse flushing biological film filter carrier anaerobic purification method which involves feeding liquid in pressurized feed tank through feed pipe, contacting through filter plate and sponges, slowly elevating fine sand, evenly penetrating in sump while feeding solution containing organic matter in filter plate and sponges, reacting marsh gas microorganism and sand, performing self-ascending biogas collection, and purifying.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic diagram of reverse flushing biological film filter carrier anaerobic purification tank.    Feed tank (1)    Feed pipe (2)    Sponges (3)    Reverse flushing pipe (4)    Sand (5)    Filter plate (6)    Marsh gas collection film (8)    Marsh gas pipe (10)    Liquid storage tank (12)    Ditch spacer blocks (14)