The Youjiang Basin was a continental margin basin during the Late Paleozoic—Triassic between Yangtze plate and Jinshajiang(Jinsha River)—Ailaoshan(Ailao Mountain) ocean which rifted on the base of South China Caledonian orogen. The basin has begun to rift at the time of the late Emsian and the branch ocean associated with the Paleo Tethys was formed during the Carboniferous. In the Permian, the ocean basin began its southwest subduction beneath the Vietnam block and evolved into active continental margin. After the latest Early Triassic, following its closure and collision, the syn collisional rocks extend in wide areas of Napo and Pingxiang. The Youjiang Basin formed a foreland basin with flysch during the Middle Triassic. So the Youjiang Basin experienced rift basin（late Early Devonian to Late Devonian）, passive continental margin（Early Carboniferous to Early Triassic ) and foreland basin（Middle Triassic）tectonic stages.