Abstract: During the 1:50000 regional geological survey in Chunzhe area of Tibet, first discovered the Calcareous clastic rock combination that is in conformity with the Xiala Formation on the north of the Chunzhe area, Xietongmen, Tibet. Also first achieve the Yatsengia coral fossils, which lived in Middle Permian. And the geological section locates in Baichabula. Author insist that the rock combination should be established a new formation alone by contrast with the geological section's rock combination, the contact relationship, the date of paleontological fossil and the area.It provides new data for the further improvement of the Palezoic stratigraphic system and basin evolution in middle of Gangdise.