Abstract: Petroleum generation in the Kongquehe slope is closely related with paleostructure during the late Caledonian Movement. Paleostructural background is the key for accumulation. The space -time matching relationship between the peak of hydrocarbon expulsion of source rock and the trap formation works as the main controlling factor. The traps with paleostructural background are favorable exploration targets. The main source rocks from Cambrian and Middle-Lower Ordovician become mature and over-mature during the middle and late Caledonian stage, and do not generate hydrocarbon during the late period. Traps are formed during the late Caledonian and the middle Yanshanian stages. The studies of accumulation stage, exploration practice and conditions of crude oil cracked gas prove that the discovered oil and gas in the Kongquehe slope may be early primary petroleum accumulations.