The 3D method for the radar mast design is put forward based on CATIA V6 platform. It comprehensively considers the practical design requirement of the radar mast and the technical difficulties of 3D model. The problems of the associated design, efficient modeling and 3D drawing in the design process of a radar mast are solved by using the multiple software functions, such as the multi-level skeleton, solid modeling, knowledge engineering and secondary development of drawing. The practical results show that the iterative efficiency and the design quality of the 3D design of the radar mast can be significantly improved by using the proposed 3D design method. This design method can also be applied to other truss-type structures except the radar mast and even more other steel structures, according to the analysis of other specific design scenes.