Abstract: Recent plant (dry grass) and mud, Quaternary mudstone and turf, Pre-Quaternary brown coal are used to study the various aspects of gas generation by anaerobic microorganism decomposition, including the asumption, method, device and results of composition analysis. It is considered that the gas generation of organism is the result of continuous unbalance over a long period of time. The quantitative relation between the amount of generated gas and buried age of organic matter is also discussed, which provides evidence for the estimation of the amount of generated biogas. Based on the fast lightening of methane δ¹³C in the gas sample series, the contradiction between the lighter isotopic index and the heavier surface methane δ¹³C in biogas exploration can be solved.