Abstract: Abundant microphytalites have been discovered in the late Sinian Dengying dolomites, Chaohu, Anhui. They can be divided into two types, four subtypes and nine groups. The oncolites with concentric and radiate structures include the Osagia, Paraosagia, Pseudosagia and Ninglangia groups. The clotted catagraphia include the Vermiculites, Glebosites, Hieroglyphiles and Nubecularites groups. The porous catagraphia include the Vesicularites group. In ascending order, these microphytalites have the following characteristics: （1） the quantities of groups and forms increase, （2） concentric laminae of oncolites become dense and there appeared radiate structure in the later stage, and （3） they become large in size and more complex in form. The assemblage appearance of the microphytalites in the area are essentially in accord with those of microphytalites in Guizhou, Hubei, Sichuan and Xinjiang. The horizon of the microphytalites underlies the Early Cambrian Anabarites-Circotheca （shelly fossil） assemblage and should be of late Sinian