Abstract: Technique of hidden surface can enhance the stereoscopic effects and intuitive effects, and make the drawing express the definite shape. The projection drawing can keep the characteristics of three-dimensional model′s topological relationships. By the way of comparing the intersection depths of projection transformation, a method of removing hidden line aimed at wireframe projection drawing is proposed. By comparing the depths of intersection, the unvisible lines can be distinguished from the visible lines. Parts of visible lines can be redrawn with the neighbor geometry relationship. Furthermore combined with human-computer interaction system which is made with VisualLISP language embedded in AutoCAD software and VB software, the hiding of the unvisible lines is realized.