NOVELTY - Producing marsh gas by anaerobic fermentation of high lignocellulose content vegetable straw, comprises crushing the vegetable straw, adding into a sealed container, adding catalyst A, mixing, pre-treating; adding catalyst B, mixing, pre-treating, carrying out solid-liquid separation, to obtain pre-treated vegetable straw; mixing the pre-treated vegetable straw with fresh dairy manure and/or pig feces, adding water and stirring to obtain a mixed solution; adding activated sludge into mixture, and carrying out anaerobic fermentation; and carrying out dehydration desulfurization treatment.    USE - The method is useful for producing marsh gas by anaerobic fermentation of high lignocellulose content vegetable straw (claimed).    ADVANTAGE - The method has fast fermentation speed, and is stable.    DETAILED DESCRIPTION - Producing marsh gas by anaerobic fermentation of high lignocellulose content vegetable straw, comprises (i) crushing the vegetable straw, adding into a sealed container, adding 3-8 wt.% catalyst A, mixing, pre-treating at 25-35 degrees C for 4-8 hours; then adding 3-8 wt.% catalyst B, mixing, pre-degrading at 30-40 degrees C for 2-8 days, carrying out solid-liquid separation, to obtain pre-treated vegetable straw; where the catalyst A includes sodium dodecyl sulfate (SDS), sodium edetate (EDTA-Na2), sodium chloride and hydrogen peroxide mixed solution, and the concentration of SDS is 0.3-0.6 wt.%, EDTA-Na2 is 0.2-0.35 wt.%, sodium chloride is 0.2-0.35 wt.%, and hydrogen peroxide is 0.3-0.6 wt.%; and the catalyst B includes magnesium sulfate, ferrous sulfate, ferric sulfate and lactic acid mixed solution, where the concentration of magnesium sulfate is 0.03-0.06 wt.%, ferrous sulfate is 0.01-0.03 wt.%, ferric sulfate is 0.01-0.03 wt.%, and lactic acid is 0.15-0.35 wt.%; (ii) mixing the pre-treated vegetable straw with fresh dairy manure and/or pig feces, adding water and stirring evenly, adjusting the moisture content to 80-90%, carbon/nitrogen ratio to (20-30):1, to obtain a mixed solution; (iii) adding activated sludge as inoculum into the obtained mixture, adjusting the pH to 7.2-8, placing in an anaerobic reactor, and carrying out anaerobic fermentation at 30-37 degrees C; and (iv) carrying out dehydration desulfurization treatment of the produced biogas, and using the gas for domestic purpose and/or driving biogas generators; carrying out solid-liquid separation of the generated biogas, and using as solid organic fertilizer for field and/or vegetable planting as foliar fertilizer.