Abstract: Methane is the hydrocarbon with highest hydrogen-carbon ratio, and is a kind of clean energy with high combustion calorific value as well. During the preparation of methane from biomass, biomass fermentation and biomass syngas fermentation are limited by the temperature sensitivity of active bacteria. This paper introduces the research progress of reaction mechanism and corresponding catalyst system of biomass synthesis gas to methane by chemical catalysts. The reaction mechanism of CO methanation and CO₂ methanation in syngas, as well as the effects of active ingredients, supports and promoters in catalysts on methanation are mainly discussed. At the same time, the catalytic hydrothermal method of biomass with mild reaction conditions is also introduced. The reaction route and research progress in recent years are briefly described. Finally, methanation reaction mechanism and efficient, stable catalysts are perspective remarked from the technical point of view.