In the design of mast and signal equipment, the design of mast such as radar mast and foremast is very complex, with more sections, frequent design changes and heavy workload. A three-dimensional (3D) design method for the mast and signal equipment is presented aiming at the design of the radar mast and foremast in the mast and signal equipment based on the CATIA knowledge engineering. A parts library of mast and signal equipment products has been established through knowledge engineering by utilizing the ability of the CATIA knowledge engineering to reuse models. By directly calling the existing parts library in the design, the product parts are organized in the hierarchical framework to complete the 3D design of the mast and signal equipment with the design knowledge as the core. The design procedure and method of the radar mast on a ship are also introduced. This design method can effectively shorten the design cycle, improve the utilization of the design knowledge and reduce the modification workload and error rate.