Abstract: Heavy oil and asphalt are found in Wutonggou and Pingdiquan formation of Permain in the east slope of Jimusaer sag. Oil of Wutonggou and Pingdiquan formation came from Pingdiquan group source rock of Permain by biomarker and carbon isotope correlateion. It is pointed that heavy oil is result of biodegradation in the paper. Oil reserveoir formation mode is established ,and heavy oil and asphalt as well as lithostrtigraphic may plug for oil and gas migration ,at last exploration direction is proposed.

Key words: Jimusaer sag, Permain, oil source, oil reserveoir formation mode, exploration direction