Abstract: To further determine the biological appearance and composition features of corals and conodonts in Poduan Formation, the geological age of Poduan Formation in south western part of Guizhou and the contrast relationship between conodonts and other categories, the typical section of Poduan Formation in Ceheng is selected to carry out the research on corals and conodont biostratigraphy. Three species of scleractinian corals, Pentasmilia zaitingnaensis, Pinacophyllum spizzensis and Gillastraea delicate, and one conodont zone, Neogondolella constricta are identified in middle-upper part of the Poduan Formation in Ceheng. Besides Neogondolella constricta, there are some other important conodonts: Neogondolella bulgarica, Neogondoela navicula, Neogondolella acuta, Neogondolella alpina alpine, Cratognathodus kochi, Ozarkodina tortilis, Prioniodina sp., Lonchodina sp., etc. in the Neogondolella constricta zone. Based on the analysis of conodonts characteristics and regional stratigraphical correlation, this conodont zone of the Poduan Formation can be comparable to the following synonym conodont zone: the upper member of Guanling Formation of Yangjuan-Chupiwa Section in Panxian of Guizhou, Guandaoyanqi of Guandao Section (2) in Luodain of Guizhou, Falang Formation of Mazheshao in Kaiyuan of Yunnan, and the stratigraphic age of the middle-upper part of the Poduan Formation, can be considered as the Illyrian substages of the Anisian stage (middle Triassic).