Abstract: In the Sino-Mongolian border area, the Early Precambrian-Cenozoic strata are widely distributed but assigned to different stratigraphic classification systems. On the basis of lithostratigraphy and tectonic evolution, the authors hold that, from Altay of China to Gobi-Tianshan of Mongolia, the strata are continuous and can be divided in unified way. With the Ertysh-Burgen fracture, Karamic fracture, Borzon fracture and East Mongolia-Diebusigo fracture as the boundary, the strata in mid-western border area can be divided into three parts, i.e., Altay zone, Junggar-Gobi Altay zone and Beishan-Gobi Tianshan zone. In this paper, the unified di-vision and correlation of strata in this area were carried out.