A workshop’s roof is designed to use steel tube trusses with the span of 24m. There are three kinds of variable cross-section splice joints of the roof truss bottom chord. Nine splice joint specimens, three for each kind, were tested to obtain their tension capacity and failure modes. A special test setup is designed to introduce the tension load to the splice joint specimen. The paper detailed introduced the test setup and method, discussed the failure load and failure mode of the joints. Experimental research indicated that the bottom chord splice joint with variable cross-section of the roof is safe, reliable, having high bearing capacity. The research also validated the correctness of the design and calculation, and provided the basis for the application of such joints in the engineering practice.