Abstract: Yanqi basin is a Mesozoic-Cenozoic coal-bearing basin formed on the Hercynian folded basement. Based on the basinal evolution, hydrocarbon source rock condition, reservoirs, cap rocks, reservoir-cap rock assemblage and trap types, this paper suggests that there are two major petroleum generation and accumulation events in this basin. The Jurassic petroleum system occurs in Bohu depression which can be divided into the northern sag petroleum system and the southern sag petroleum system in plane and into Jurassic primary petroleum system and Tertiary secondary petroleum system in longitudinal direction.

Key words: intermontane basin, petroleum gelogogy, reservoir-forming stage, petroleum system