Abstract: The organic matter abundances are considered as a very important indicator for the evaluation of source rocks.The heterogeneity of source rocks,production of inorganic CO₂ and hydrothermal hydrocarbon generation play an important role in the restoration of organic matter abundances in the source rocks.The restoration of organic matter abundances in the source rocks from the Damintun depression on the basis of the thermal simulation experiment and matter conservation law shows that the source rocks from the first member of the Shahejie Formation and Dongying Formation are more promising areas in the Damintun depression.