Two semi-rigid beam-column connection specimens with T-stubs of steel frame were designed. The impact tests using drop-hammer were conducted to simulate the collapse behavior under impact loading. The influence of thickness of T-stubs flange and web for the beam-column connection on the impact resistance of steel frame substructure was investigated. The failure modes and time histories of impact load and deformation were obtained，and the dynamic responses of the impact load and deformation time histories were analyzed as well as the dynamic rotation and energy dissipation of the substructures. Test results show that the failure modes of T-stub beam-column connection specimens mainly include the fracture and bending deformation of T-stub flange and web as well as distortional deformation of steel beam web. The rotation capacity of two connection specimens were dominated by the T-stubs，and their maximum rotations are less than the FEMA350 design limit （θ = 0.109 rad） due to the premature failure of T-stubs. The energy dissipation and ductility of semi-rigid beam-column connection specimens with T-stubs are inferior to the ordinary welded rigid beam-column connections. The finite element （FE） analysis model of T-stub beam-column connection was established using ABAQUS software. The internal force development of specimens during the impact loading was analyzed and it demonstrated that the T-stub beam-column connection with design of partial strength and semi-rigid connection degraded the formation of catenary action.