NOVELTY - Method for utilizing external hydrogen for promoting rapid methanogenesis of organic waste, involves mixing sludge with domestic waste, performing anaerobic fermentation of the mixture, generating external pure hydrogen from bottom of the mixture, stopping generating the pure hydrogen when the content of the methane in the gas from the outlet is reduced to 1% or less per hour and generating the hydrogen to carry out anaerobic fermentation periodically.    USE - The method is useful for utilizing external hydrogen for promoting rapid methanogenesis of organic waste.    ADVANTAGE - The method is simple, cost-effective, environmentally-friendly and suitable for medium and small-scale landfill yard, and exhibits excellent social and economical benefits.    DETAILED DESCRIPTION - Method for utilizing external hydrogen for promoting rapid methanogenesis of organic waste, involves mixing sludge with domestic waste in the weight ratio of 1:(2-4), where the content of volatile substance (VS) in the mixture is 20-65% and water content is 18-68%, performing anaerobic fermentation of the mixture at 35-37 degrees C for 3-5 periods based on pH of 6.5-7.5, where each period is 7-14 days, generating external pure hydrogen from bottom of the mixture at 1.1-5.5 MPa at the second day of each period, at the same time, continuously monitoring the gas component and content at the gas outlet at the top of the mixture by vapor gas chromatograph apparatus, stopping generating the pure hydrogen when the content of the methane in the gas from the outlet is reduced to 1% or less per hour, ending one period of anaerobic fermentation, repeating the operations and generating the hydrogen to carry out anaerobic fermentation periodically, when the leading quantity is 50-150 ml hydrogen/kg VS, the largest day yield of the methane is 3.65 l/kg.day, which is 2.81 times by the yield when not adding hydrogen, and the concentration of the methane is improved to 75.5% from 33.2%, and conversion rate of the organic waste is converted to energy methane and improved to 2.93% from 1.04%.