In this paper, design specifications of circular steel tubular welded States and EU are studied thoroughly. With detailed analysis cation, failure mode and ultimate bearing capacity of joints, and comparison joints in China, United about the joints classifi- the design bined with practical examples. The results show that the wall thickness proposals are presented tom- increased is one of the most effective way to improve the joint strength and the joint strength can be improved by increase the dia- metrical ratio between the branch pipe and main pipe.