Abstract: The Sanjiang fold system is an Early Indosinian fold system formed in the principal Indosinian fold phase at the end of the Middle Triassic. Owing to the complex structure of the orogenic belt, its overlying Upper Triassic likewise has complex sedimentary features. In order to compile a geological map of the region where the Sanjiang fold system is distributed, study the Upper Triassic lithofacies and formations, sedimentology and paleogeography and predict the prospects of stratabound deposits, the author puts some ideas about the sedimentary types and stratigraphical correlation of the Upper Triassic from such respects as the structure of the section, rock associations, fossils and contact relationships.