Abstract: The formation and evolution of Triassic Qiangtang basin are controlled by Lazhulong-Xjjinwulan rift and Bangonghu-Dingqing rift. In .early and middle Triassic, the basin is at the beginning of the formation and the deposition is limited in northwestern part of it. In the early peri- od of late Triassic, these two rifts initiated shaping and by the basin's faulting and subsiding, three formations are developed as clastic formation,carbonate formation and mediate-basic volcanic formation. During the middle period of late Triassic，the basin is in relative stable stage completely submerged by sea water. In the late period of late Triassic, Lzhulong-Xijinwulan rift is closed followed by large-scale marine regressing,hence the depos itional formation dominated by sand-shale intercalated with coal seam or "coal line" is shaped.

Key words: Qiangtang basin, Triassic, formation, evolution