Abstract: The Late Carboniferous-Permian Cathaysia floras are distributed mainly in East Asia, specifically in the North China, South China, Tarim and Indo-Chlna blocks. Based on the suturing time of these blocks and the Late Carboniferous-Permian sfiratigraphic and paleontologic characteristics there. the authors believe that these blocks had converged into one large continental block before the Carboniferous and call it Cathaysia as it is characterized by the development of Cathaysia floras. This land was located in the Paleo-Tethys Ocean between Angara and Gondwana, and Paleo-Tethys separated it into the northern and southern branches. In the Late Permian, Cathaysia drifted and collided with Angara finally at the end of the Permian, forming the Tianshan-Beishan-Inner Mongolia suture zone of the north branch of Paleo-Tethys. At the end of the Early Triassic, the Tibet and Sibumasu blocks separated from the north margin of Gondwana moved northward and collided with the southwest margin of Cathaysia, forming the Kunlun-Sanjiang （Three-Rivers）suture zone. Thus Cathaysia became a part of Laurasia.