Abstract: In recent three years,important achievements have been obtained from many times of petroleum geological investigation and comprehensive research.Oil sand is discovered in the Tertiary sandstones and the Jurassic carbonate rocks.The Jurassic and Tertiary megathick strata is outcropping from ground.Hydrocarbon source rocks are mainly black argillaceous rocks and carbonate rocks distributed in the Middle-Lower Jurassic (J₁₊₂) strata.Argillaceous source rocks make up 32.8-46.1 per cent of the Middle-Lower Jurassic stratum thickness,while cardonate source rocks,which are mainly developed in Heishuigou region,amount to 30.5 per cent.Comprehensive study on the analytical results of outcropped surface samples show that argillaceous source rocks are good hydrocarbon source rocks with the good types,high abundance and high maturity of organic matter,and carbonate source rocks are the best with the well types,high abundance and high maturity of organic matter.Widespread argillaceous source rocks are the most major hydrocarbon source rocks in the Gesi Fault Trough,and carbonate source rocks mainly distributed in the east are important hydrocarbon source rocks.