Abstract: A simulation experiment was made on kerogen from shales in the lower Xiamalin Formation of the Proterozoic in North China.Certain characteristics and the law of the thermal evolution for the organics from the lower Xiamalin Formation have been revealed in the study.Furthermore, with the basis of experimental results, an evolution model of oil and gas generation for the middle and upper Proterozoic is developed, and the limit of maturity index is marked, which provide the evidences for the determination of organic maturity and the assessment of petroleum resources.