Abstract: The beam-column semi-rigid joint becomes more and more widely applied recently in the engineering practice due to various advantages． But the study on the mechanical properties of the joint is far from perfect in China． In the paper，four sets of specimens of the beam-column semi-rigid joint of the concrete-filled square tube were made． The study and description of mechanical behavior and failure mode of the joint under the low cycle cyclic loads were also done． It is concluded that the joint has good ductility and the capability of energy dissipation by the analysis of the various indicators． The study provides some reference for the node design of steel structure．