In view of few studies on the effect of weld access hole on the mechanical properties of beam-column joints, tests and finite element analysis were conducted to investigate the mechanical properties of each component of the T-shaped steel beam-column joints. The results show that increasing the strength of panel zone is detrimental to the deformation performance of the specimen, but the maximum bearing capacity improves. The bending moment distribution of the beam is affected by the weld access hole at the beam-column joints in the analysis model (AM). At the beam end of beam-column joints, the bending moment of the beam web tends to increase due to the stress concentration. Meanwhile, within the range of 0~80 mm along the axial direction of the beam end, the bending moment of the beam web is relatively small, especially the minimum bending moment of the beam web is located at near 35 mm along the axial direction of the beam end. Conversely, the bending moment of the beam flange is relatively large within the range of 0~80 mm along the axial direction at the beam end, which is caused by the decreasing bearing capacity of the beam web due to the effect of the weld access hole and the concentration trend of stress around the weld access hole under invariable external loads. And hence the smaller the load on the beam web, the greater the load on the beam flange at the axial of the beam end. The strength of the panel zone is positively correlated with the shear load on the beam web at the beam end of the AM model. As the strength of the panel zone decreases, the shear load on the beam web at the beam end also decreases.