Large-caliber UWB Bow-tie antennas have excellent performance, but are often difficult to process and forming. In order to solve the problems in the forming process of a large-caliber ultra-wideband bow-tie antenna, the structure of the antenna was decomposed into several parts including bow-tie dipoles, back-cavity, metal pillars and non-metallic columns. Then the process difficulties of each part were analyzed. Upsetting was used for machining the large-sized back-cavity and a processing equipment was used of machining the non-metallic columns. Also there was big difficulty in the assembly and welding. However, electron beam welding can be an effective method. After the antenna was formed, antenna tests showed that the antenna with above forming process has good performance. This study contributes to improving the design of UWB bow-tie antennas and promoting their applications.