Abstract: Thanks to the efforts made by generation after generation, the petroleum geology of China has been established in the 20th. In view of the three key elements to forming oil-gas reservoir, it is recognized that the principal features of this scientific discipline are the terrestrial origin hydrocarbon generation, repeated migration and compound accumulation of oil-gas, and all these features reflect the complexity of petroleum geologic conditions. And, it is due to the complicated geological structural environment resulted from the separation,merging, collision of plates which consists of land nucleus in geologic history,and it results in the multiple cyclic state of China's land nucleus development. Facing such situation, at the beginning of the new century, the Chinese geologists will not only further enhance their own effort but also have to turn theirs eyes from inside to outside,and strengthen their mode of thinking on the basis of systemalogy.

Key words: terrestrial oil generation, secondary migration, compound oil-gas field, oil-bearing basin