Abstract: Drawing interpretation and transformation are a difficult problem in international economic and technical exchange. According to orthographic projec tion principle, we found out their generalities and differences of Chinese-fore ign technical drawing projection, and reached the law of view transformation. We build a drawing replacement theorem, which can simplify complicated and overela borate interpretation work of engineering drawing and improve the efficiency gre atly. Work out technical documents using the method of actual transformation and draw using CAD. It just needs “settle on”、 “copy”、 “displace” and “ stick” to have finished the work that the first angle of projection transforms mutually into the third one. When we operate it on construction site, we can us e both actual and ideal transformations, and apply and diffuse them.