Abstract <p>The Xujiahe Formation in the upper Triassic is characterized by 5 members (Member-1 to Member-5), representing three cycles from coarse to fine. The overall facies architecture of Xujiahe Formation implies deposition in a braided delta environment. High resolution sequence stratigraphy was performed based on outcrops, core observations, well logs and seismic interpretations. The Xujiahe Formation is interpreted as a 3rd sequence, comprising a transgressive systems tract (TST) and a regressive systems tract (RST). Within this 3rd sequence, six 4th sequences are recognized. The TST(FS1–FS4) mostly comprises subaqueous distributary channel fills ,distal bars, and shallow-lake facies, capped by the Belt Child mudstone that includes the maximum flooding surface(MFS). The RST(FS5–FS6) mainly contains subaqueous distributary channel deposits. Based on thin-sections, high-pressure mercury-intrusion analyses, the sandstone cements primarily consist of chlorite, calcite , secondary quartz and dolomite, filling pores. This study reveals quality reservoirs are mainly distributed in the lacustrine transgression and retrogradation strata in the base-level rising stage and in the stable period of the transition from base-level decline to base-level rise, but are seldom developed in the lacustrine retrogradation strata in base-level falling stage. The variation of accommodative space and sediment supply controls the vertical sand body assemblage, the distribution of sand body and the distribution characteristics of high-quality reservoirs in the study area.</p>