Abstract: The detail sedimentation study of the Middle Jurassic outcrops consisting of Xiufeng,Er-shierzhan,Emuerhe and Kaikukang formations respectively,indicated that alluvial fan,fan delta,braided river delta,lake floor fan and lacustrine facies were developed from Xiufeng to Kaikukang formations in the Middle Jurassic of the Mohe Basin.The alluvial fan and fan delta facies were developed in the Xiufeng formation,the braided river delta in the Ershierzhan and Emuerhe formations,alluvial fan and fan delta in the Kaikukang formation,and lake floor fan and lacustrine facies in all above formations.The sedimentary evolution from Xiufeng to Kaikukang formation was as alluvial fan fan delta lacustrine to braided river braided river delta lacustrine to alluvial fan fan delta lacustrine.Such a sedimentary evolution resulted in the development of source rocks,reservoirs and cap rocks.Therefore,there is petroleum potential in the Middle Jurassic of the Mohe Basin.