Abstract: Intuitive understanding of basin characteristics such as early paleostructure, paleoenvironment and paleocurrent could be got based on paleogeomorphy restoring prototype basins, laying solid basis for further oil and gas exploration. Taking Wulanhua sag as an example, this paper analyzed the structural characteristics of Mesozoic residual sags in Erlian Basin, combined multiple paleogeomorphic restoring methods including the geophysical method, the residual thickness method, and sequence stratigraphic method, used 3D visualization technique as a medium, and truly refl ected the structural development history characteristics of the sag. Paleogeomorphic restoring shows that Wulanhua sag took shape during the sedimentary stage of Early Cretaceous Aershan Formation; the sedimentary stage of Tenggeer Formation is the expansion stage of fault depression; lacustrine basin shrank and structure reversed during the sedimentary stage of Saihantala Formation, which as a whole exhibited the characteristics that source rocks were thick at early stage and eroded at late stage.