The anaerobic fermentation method, which was used in biogenic gas resource appraisal, failed to reflect or describe the gas generation period. In consideration of this tough problem, a chemical kinetic model of biogenic gas generated from organic matter is constructed according to chemical kinetic theory, and the kinetic parameters are calibrated with the data of simulation experiment. On the base of this, taking the influence of bacterium concentration and temperature on the kinetic parameters into consideration, the initial application of the chemical kinetic model in the Qaidam Basin shows that the biogenic gas generation rate increases with the buried depth firstly, and then decreases when it reaches to the maximum (corresponding to a buried depth of 600 m). This conclusion is similar to the previous study result, so this model can be used to appraise the biogenic gas generation period.