Biogas is one of the ultimate products of sediments in the early stage of diagenesis controlled by biochemical function.The conventional biological gas production pattern believed that the sedimentary organic matters were degraded into small molecule substrates in anaerobic environment by microorganism which could be used by methanogen bacteria and then converted to methane through acetate fermentation and carbon dioxide reduction.This paper breaks through the traditional understanding and puts out that low temperature thermodynamic and microbiological action are the main mechanisms for biogas production in eastern Qaidam Basin.The traditional model overstresses the role of inherited active organic matter.The analysis shows that the Quaternary inherited active organic matters in sediments are not abundant.Study indicates that it can produce some secondary active organic matters which can supply important nutrition substrates source for the biomethane buried at certain depth.