The invention provides a method for increasing the methane yield of sludge anaerobic digestion by utilizing an iron/carbon/biological enzyme coupling technology, which comprises the following steps: S1, weighing Baijiu koji, putting into a triangular flask, adding distilled water, carrying out constant-temperature water bath for 0.5-1.5 hours, then carrying out suction filtration by using quantitative filter paper, and screening out large-particle substances and part of mould and saccharomycetes to obtain a leaching solution for later use; s2, injecting sludge into an anaerobic reaction container, adding nano zero-valent iron, activated carbon and the Baijiu distiller's yeast leaching filtrate prepared in the step S1, continuously filling inert gas, removing oxygen, and sealing the reaction container; and S3, carrying out constant-temperature anaerobic digestion on the sealed reaction container. The reinforcer (nano zero-valent iron, activated carbon and distiller's yeast leaching liquor) adopted by the method is low in cost, cheap and easy to obtain, small in addition amount and low in operation cost, has a good application prospect, and solves the technical problems of low substrate conversion rate and low biogas yield in the anaerobic digestion process in the prior art.