The Bayan Har block, as the main body of Tethys, is located in the northeast of the Tibetan Plateau. In-depth study in this area is not only of great importance for determining the evolution of Tethys but also of important practical significance for the research on metallogenesis related to tectonic evolution and minerals distribution in this area. The Bayan Har Group is located in the Bayan Har block, where the research on its provenance is insufficient. Its detrital and chemical components can reflect the features of the provenance and tectonic setting. The authors' researches on petrological characteristics, depositional setting, geochemical indices and geochemical discrimination diagrams of clastic rocks of the Bayan Har Group, together with previous researches on paleocurrent of Bayan Har Group clastic rocks, suggest that the Bayan Har Triassic sedimentary basin was based on the splitting of the old basement, the process of rift expansion did exist, the depth of water was increased, the tectonic setting was mainly characterized by the continental island arc and active continental margin, and the deposited sediments was derived from felsic rocks of upper continental crust of East Kunlun orogenic belt in the north.