In this paper, the different sizes of enlarged weld access hole (EWAH) in steel beam-column connection are presented. Based on the commercial nonlinear finite element code ABAQUS, firstly, the sequential welding process is simulated, and the non-linear pseudo-static is performed. Through the comparison of results between the FEA and finished pseudo-static experiment when EWAH size is adopted by x=115mm and y=35mm, it is demonstrated that this analysis method is rational and effective, moreover, the stress concentration effects and cracks are discovered. And then the FEA method still obtains, the EWAH size y=35mm is changeless, the nine structural models are made up for only considering the value range from x=70mm to x=110mm. Furthermore, the impacts of the EWAH size on mechanical behaviour are discussed, and the reasonable geometric range is proposed.