Abstract: Selecting Q345 grade steel as the research object, this study explores the performance of T-shaped joints in building steel structures under different welding speeds. Using Hypermesh software for modeling, the system analyzed the effects of three welding speeds of 300mm/min, 400mm/min, and 500mm/min on the residual strain and overall performance of T-shaped welded joints. The results showed that a welding speed of 300mm/min caused excessive temperature in the weld area, increasing the risk of joint damage; The welding speed of 500mm/min increases the difficulty of operation and may affect the welding quality due to insufficient heat input. In contrast, a welding speed of 400mm/min has been proven to be the optimal choice, which not only effectively controls residual strain (below 0.025), reduces radial displacement, enhances structural stability, but also maintains excellent microhardness, thereby comprehensively improving the comprehensive performance of the welded joint. Therefore, this study suggests prioritizing the use of a welding speed of 400mm/min in T-shaped welded joints of prefabricated steel structures in order to maximize joint performance and minimize residual strain.