Abstract: On the basis of thermal simulation data of different types of kerogen, the author of this paper proposes the hydrocarbon yields of source rocks during the stage from maturity threshold to peak oil generation, i.e. 14.07% for kerogen Ⅰ, 16.50% for kerogen Ⅱ and 18.28% for kerogen Ⅲ. Most of the hydrocarbons were generated after the stage when peak oil generation have been reached. Taking Bi Well No.08 in Biyang Depression as an example, hydrocarbon generation pattern is fundamentally consistent with the results of thermal simulation mentiond above.