The entire roof of the universal studios station of the East extension project of Beijing metro line 7 is based on the main structure of the box,the umbrella column joints of the circular tube conversion box is used as the core supporting member of the entire roof structure. Its welding quality and machining dimensional accuracy are particularly important. From the perspective of processing and production,the key points and difficulties of the umbrella column joints are deeply analyzed,the interpass tearing cracks and welding sequence tending toward dimensional control are prevented,the operability of the umbrella column joints and the reliability of the structure are ensured. This provides some reference for futrure processing of the umbrella column joints.