In order to investigate the seismic performance of diaphragm-through joint betweencon-Crete-versedfilled square steel tubular column and steel beama quasi-static experiment under low re-cyclic load of one full-size T-shaped specimen of diaphragm through style beam-columnjoints was designed.with the hysteretic hoops acquired from the experiment, the skeletoncurvesofspecimen and the equivalent viscosity coefficient, with which the energy dissipation of the joint maybe weighted, were calculated.The failure process and feature of the specimen were described andductility, energy dissipation were analyzed.By using ANSYSence of the seismic performance by the thickness of protrusionthis paper discussed the influ-of the diaphragm and the strength of theconcrete core.Based on above all, we can get a conclusion that the diaphragm-through style beam-column joint have a higher bearing capacity and good ductility, energy dissipation capacity and hasa strong seismic performance.