In order to study the load-carrying capacity and ductility behavior of steel square stub co-lumns with T-shaped stiffeners under combined compression and bending loads, a three-dimensional elastic-plastic finite element analysis model of steel square stub columns with rectangular stiffeners was established, taking into account initial geometric defects and welding residual stresses. The accuracy of the finite element model was verified by comparing it with existing research results. A series of parame-tric studies were carried out to investigate the effect of normalized flange width-thickness ratio, norma-lized stiffener’s slenderness ratio and axial compression ratio on the maximum flexural capacity and ultimate strain of steel square stub columns with T-shaped stiffeners. Based on the results of the parametric analysis, the calculation formulas for predicting the maximum flexural capacity and ultimate strain of these stub columns were proposed. The research results indicate that as the normalized flange width-thickness ratio, normalized stiffener’s slenderness ratio and axial compression ratio decrease, the maximum flexural capacity and ductility behavior of steel square stub columns with T-shaped stiffeners are improved.