Abstract: The region of Hengduan mountain is a very natural region in floristic nature. Its seed plants' flora is abundant in species, genera and families, complex in geographical elements, strik-ing in endemism and vicariance, and basically temperate in nature. According to the degree of abundance in endemic species and some physiographical features, the region can be floristically divided into three subregions: subregion of NW Yunnan and SW Sichuan, subregion of NW Sichuan to SW Gansu and SE Qinghai, as well as subregion of E to SE Xizang. Based on the ana-lysis of its floristic elements, the region is certainly a knot for clarifying the questions about the relationships between the florogenesis and the plate-tectonics, about the origin of the North temperate flora including that of E Asia, N America and Europe.

Key words: Region of Hengduan moutain