Abstract: Borrowing the process flow of design, fabrication and assembly of the prefab house, and using the Auto CAD platform, the CAD assembly method for shaped tube pass is elaborated, focusing on the three main aspects, i.e., design of deformation curve parameters of the“ round-shaped” pass, “fabrication” (drawing) of the independent deformation curve and“assembly”thereof. It is proposed to take full advantage of the CAD principle, the adverse thinking deformation pass principle, the nominal dimension principle and the streamlining principle. Thanks to the said CAD assembly method, the miscellaneous calculation steps normally asked for design of shaped tube pass is left out so as to obtain reasonable deformation of the shaped tube, and also get the design efficiency enhanced.