Abstract: The Tertiary System in Gansu and its neighbouring areas consists all of sediments of continental lake basin and intermontane depression types. As there existed many problems on the stratigraphic division and age assignment in the past, confusion arose in respect to the stratigraphic correlation. On the basis of the paleontologic data combined with the depositional character- istics, rock associations, ore potentiality and contact relationships, this paper proposes a rational scheme of stratigraphic division and correlation and sum- marizes the stratigrphic features and ancient biotas of various sedimentary basins.