Natural gas from coal formations as a relatively clean unconventional fuel with lower emissions of environmental pollu- tants than coal and petroleum products has received more concern. As the main component of coalbed methane, CH4 is original- ly thought to be thermogenic, but more envidence of isotopic composition for CH4 and CO2 and formation water has shown that biogenie methane is widespread in coalbeds and sediments. It is estimated that in nature biogenic methane accounts for 20% -65 % of the total natural gas production. Due to the develepment of new molaeular methods, the subsurface microibal ecosystem has been uncovered. Based on the simulation of microbial methane produciton in the lab, the generation and accumulation of CH4 in coal seams have been greatly accelerated. However, this complex transformation process of coal to methane is not fully understood, so we need more research on the mechanism of initial degradation of solid coal and what factors control the methane production and producing rate.