Abstract: With field geological survey, the stratigraphic sequences and structural characteristics of the southern margin of Mohe Basin are studied. The result shows that the south of the basin is covered mainly by Middle Jurassic fluvial and lacustrine sedimentary rocks and Upper Jurassic and Cretaceous volcanic rocks. Affected by the extensional process, normal faults and spade faulting are developed in the south of the basin. The southern margin of the basin has the characteristics of fault-depression basin. The basin is formed in a long course. The southern boundary of the Mohe Basin is also determined by the study.