The Late Jurassic volcanic stratigraphy in Duolun area are divided into volcanic activities microcycles of Manketou Obo , Manit and Bayangol. This p ape r deals with characteristics of the volcanic activities rhythm in the region fr om the stages, periods and irreversible of the evolve of the earths history, which is based on the study of the rock association，lithofacies，tectonic and s tructure and their changes. Furthermore, the hierarchy and characteristics of th e volcanic activities rhythm are classified from the spacetime. The formation of different hierarchy is discussed.