The present paper reports descriptions and microscopical studies on Dai medicine" Guo sha" (Broussonetia papyrifera) , which is also the ethnomedicines of some minority nationalities in China. The diagram and the detailed drawing of the transection of the root, as well as microscopic drawing of its powder, were drawn in the studies. It was found that there are distinct microscopic characters of the transection and the powder which can serve as evidence for identification of the ethnomedicine.