The first large- area continuous petroleum (oil) reservoirs, which was recently discovered in the Lower Triassic Baikouquan Formation of the petroliferous Mahu sag, Junggar Basin, northwestern China, is an important supplement to the study of continuous hydrocarbon reservoirs globally. However, the reservoir forming mechanism and relevant accumulation model have not been well constrained. To improve the understanding of these issues and provide some references for theoretical study and exploration, this study investigated hydrocarbon accumulation conditions and related models based on the basic petroleum geological conditions, i. e. , source rock, reservoir rock, cap rock, trap, migration and preservation, along with the reservoir characteristics. Results show that multiple factors provide favorable geological conditions for these large- area continuous oil accumulations, including sufficient oil and high- quality gas sources generated from the lower Permian Fengcheng Formation, effective and large- scale fan delta- front sandy conglomerate reservoirs, multiple blocks for sealing and preservation composed of tight conglomerates and mudstones in the delta plain and the closed faults, good migration systems of high- angle faults, as well as relatively smooth and continuous structural background. In these favorable conditions, high maturity oil and gas generated from the Fengcheng Formation entered the underwater channel sandstones and sandy conglomerates of relatively good physical property along the high- angle shear faults between hydrocarbon sources and reservoirs. These factors control the oil enrichment level, and the hydrocarbon accumulation in the study area is dominated by triple controls, including fan delta, faults, as well as high reservoir pressure, forming fan- fault- pressure- controlling continuous hydrocarbon accumulation in the large- scale gentle slope fan delta system deposited in shallow water. The Baikouquan Formation reservoirs have the characteristics of light oil containing gas, wide occurrence of micro cracks and abnormal high pressure. These determine the high oil production from the generally low porosity and low permeability conglomerate reservoirs. Therefore, the updip slope area with faults connecting the source and reservoirs, abnormal high pressure and subaqueous channel sand conglomerates of the fan delta- front facies are favorable for exploration.