The Late Triassic Tumengela Group and Jiezha Group in the central Qiangtang basin are distributed in the southwestern and ortheastern sides of the Tumengela Fault. Bivalves assemblages of them show that they are middle—late Norian stage，Late Triassic. Based on the palaeosalinity， paleoclimate， and trace element contents， as well as lithochemical data， it is concluded that the Tumengela Group in southwestern region sedimented in shallowwater environments of lower salinity， oxidation，higher evaporation and lkalescence； then， the Jieza Group in northeastern region sedimented in deepwater environments of higher salinity， deoxidation and warmhumidity. Based on types of meter scale cyclic sequences and their fabricfeatures of faciessecuess， a complete secondorder cycle of relative sea level change occurred during the Late Triassic， contained mainly 4 thirdorder cyc les. The basic characteristic of the Late Triassic strata is unanimous， the feature of paleogeographical framwork was that the southern part was shallow water and the northern part deep water； the differences of them are originated from sedimentary facieschange and diachrononism. So， it is worth rediscussing whether the Tumengela fault is the boundary of Xizang(Tibet)—Yunnan strataregion and Yangtze strataregion or not.