The monotonous static horizontal load experiment was carried out on 1∶2 and 1∶3 scale joints model to investigate the failure mode and ultimate bearing capacity of steel-concrete composite truss joints. The behavior of loading process, the comparison of the ultimate bearing capacity and failure mode were presented in detail, and the factors that influence the mechanical behavior of joints were found. The experimental results showed that failure mechanisms include the cracking mode of concrete, compression buckling and tear destroy of plate. The ANSYS software was used to analyze the specimens, and the results were in good agreement with the tests. The result of comparison with finite element showed the weak parts of different scale joints and how to effectively improve the bearing capacity. Test results can provide reference and theoretical basis for the similar projects on the joint design.