Five joint specimens were manufactured in this study based on the criterion of strong column and weak beam in order to investigate the seismic performance of the endplate-bolted joint of concrete filled square steel tubular with a high-strength core-to-steel beam. A pseudo static test was conducted to investigate the failure mechanism of joints and the effects of axial compression ratio, FRP thickness and the presence of high-strength core on the seismic performance. The behavior of joints before and after replacing steel beams were compared. The test results showed that all specimens eventually failed due to the formation of plastic hinges at the steel beam ends. The joints showed a high bearing capacity, good energy consumption capacity and ductility under this failure mode. The joint encasing the high-strength core exhibited a higher bearing capacity but smaller ductility. The initial stiffness and energy dissipation capacity of the joints were improved as the FRP tube thickness increased. Compared with the original specimen, the energy dissipation capacity, ductility and initial stiffness of the beam replacing specimen were smaller. The deformation analysis results showed that the composite column in the panel zone of the joint mainly undertook the bending deformation, whereas the shear deformation of the joint was mainly carried by the beams. The joints were classified as rigid joint according to the initial stiffness.