Abstract: Low-permeability glutenite reservoirs of Baikouquan formation are the major targets for petroleum exploration in Junggar basin.Five reservoirs of the Triassic Baikouquan formation have been found and proved in west slope zone of Mahu sag in the basin. The comprehensive study suggests that the west slope zone is of four favorable conditions for hydrocarbon accumulation: several sets of high-quality source rocks of the Permian continuously provide hydrocarbon for the reservoir; dessert spots occur in the low permeability reservoirs; high efficient transport systems are shaped by deep faults and unconformities, and the regional cap rocks are developed here. Also, the fan delta frontal facies belts distributed in this area have better reservoir property, there exist multistage hydrocarbon charging and good preservation conditions for late highly matured hydrocarbons, and the oil is lighter and contains natural gas, all of which could be the main reasons for its hydrocarbon enrichment