In order to realize the 3D visualization of steep terrains like level terraces, a new Offset Line Method (OLM) -based visual method is put forth in this paper. The constrained feature lines and their Bottom Offset Cliff Lines (BOCLs) are collected and considered while building DEM. Therefore, the steep terrains like level terraces with steep steps can be visualized well. Our case study shows that the steep terrains can be visualized well if the constrained feature lines and their BOCLs were considered according to the principles of OLM while building Triangulated Irregular Networks (TINs) or grid-based DEM. how to determine the optimal value of ∆d needs further study in the future.