NOVELTY - A Trichoderma viride M20 strain (CGMCC 4732) capable of producing cellulose degradation enzyme, is new.    USE - The fermentation liquor of T.viride M20 strain is useful for producing cellulose degradation enzyme which is used for degrading urban green waste, such as the fallen leaves and lawn grass, and for producing reducing sugar (all claimed) which is used for producing single-cell protein and fuel (ethanol).    ADVANTAGE - The T.viride M20 strain is environmentally-friendly, produces reducing rapidly, and reduces energy shortage and several formidable problems faced by contemporary people.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for method for culturing T.viride M20 strain for producing cellulose degradation enzyme, which involves activating the M20 strain on a flat board, and culturing the M20 strain on potato dextrose agar (PDA) flat board, where the PDA flat board is prepared by peeling 200 g of potato, cutting the potato into blocks, boiling for 30 minutes, filtering using gauze, filtering the juice, adding 1% of glucose and 2% of agar and metering the volume to 1 l, culturing the strain for 3-5 days at 30 degrees C, when the green spore grows out, obtaining four blocks of bacterial colony with 1000 mu l round end of spear tail, and inoculating the colony in seed culture medium, where the seed culture medium comprises (in g): corn powder (40 meshes) (3), bean cake powder (1.5), magnesium sulfate heptahydrate (0.05), dipotassium phosphate (0.2), and water (100 ml) and pH of the seed culture medium is neutral, and each 250 ml bottle is packed with 50 ml culture medium, culturing the M20 seeds for 2 days at 150 revolutions per minute (rpm) and 30 degrees C, adding 1-2 ml of production enzyme in the culture medium, where the production enzyme is prepared by mixing (in g) ammonium sulfate (0.5), peptone (0.5), potassium dihydrogen phosphate (KH2PO4) (0.5), potassium chloride (1), magnesium sulfate heptahydrate (0.5), calcium chloride (0.1), yeast powder (0.5), microcrystalline starch (5), water (1000 ml), and pH of the production enzyme is 6, culturing the strain at 150 rpm and 30 degrees C, and fermenting for 7 days.