The load-bearing performance of tubular joints mainly depends on the detailed structural measures in the joint domain. In this paper, the 68# joint of the lower chord of the space steel truss with welded tubular joints on the roof of Taiyuan South Railway Station was taken as the research object. The full-scale static test and numerical finite element method were used to explore the effect of the detailed structural measures of the joint domain on the static performance of the joint. The research shows that the proposed “concrete + transverse diaphragms” structural measures can fully meet the mechanical performance requirements of tubular joints; There is a reasonable matching interval between the ultimate bearing capacity of the joints and the arrangement of the transverse diaphragms, with the “C40+5 transverse diaphragms” possessing the best bearing capacity, which is 2.06 times the design load value; compared with the arrangement of the transverse diaphragms, the contribution rate of the filled concrete in the joint domain to its ultimate bearing capacity gradually decreases from 54.16% to 5.05%; the strength grade of the filled concrete in the joint domain has no significant influence on its ultimate bearing capacity.