Abstract: In the Azhi area,Yuanjiang county,Yunnan province structure is very complex and thereoutcrops a sequence of arenaceous-argillaceous rocks and carbonate rocks,which was for-merly assigned to the Dalongkou Formation of the Middle protero zoic Kunyang Group.Dur-ing recent 1:50000 regional surveys, fossils organisms of 12 groups were discovered therein,which were identified to be mainly late Middle Devonian to early Late Devonian elements.Onthe basis of the features of lithologic associations,the Haikou Formation and Zaige Formationmay be distinguished.