The Triassic in the Qomolongma area, southern Xizang(Tibet), was deposited under an extensional tectonic setting from the Pangea supercontinent to continental rift. From the Induan to Rhaetian, 12 depositional sequences (3rd-order) have been recognized, which can be grouped into 5 sequence sets and belong to 2 mesose-quence (2nd-order). Four marine transgressions, respectively at the beginning of the Triassic (ca. 250 Ma), Early Anisian (ca. 239 Ma), Early Carnian (ca. 231 Ma) and Early Norian (ca. 223 Ma), are particularly of significance and can be used as markers for stratigraphic correlation widely across continents. The study shows that during the Triassic the Qomolangma area experienced a sedimentary evolution from epicontinental sea to rift basin with the turning point at the Late Carnian (ca. 228 Ma). During the Early and Middle Triassic, the area was under epeiric sea, with carbonate ramp to mixed shoal environments predominant. In the Late Carnian , strong extension initiated listric faulting and rapid basement subsidence, thus resulting in the onset of rift basin. From the late Norian to Rhaetian, it manifested as a rapid basin filling process in the area. Coupled with the long -term global sea -level fall in the latest Triassic, the excessive terriginous influx led to the shifts of environment from deep -water prodelta to shore and finally to fluvial plain.