In order to examine the flange local stability of T-rib stiffened plates under compression, considering the variation of flange width thickness ratio, T-rib stiffened plates with Q345 strength (5 pieces) and Q420 strength (4 pieces) were fabricated to carry out the local stability axial compression test, and the finite element (FE) models were established to compare with the test. The influence of different material constitutions, simplified welding residual stresses and local initial geometric imperfections on the mechanical properties of the flange were analyzed. The simplified calculation formula for the local stability of the flange was obtained. The results show that both the test and the FE model are subjected to the local buckling failure near the flange height of 1/2, and the larger the flange width-thickness ratio is, the earlier the specimen comes to local buckling failure. The FE models are simulated by an ideal elastic-plastic constitutive model. With increase of the relative flange width-thickness ratio, the axial stiffness of the component decrease because of the inclusion of residual stress. The coefficient of stability is smallest when local initial imperfections are included. The curve of the simplified formula for the flange local stability fitted by cubic polynomial is close to the trend of the Eurocode curve, while the curve fitted by Perry formula is close to the trend of the Chinese and American standard curves. The trend of formula curves fitted with different steel strengthes is basically the same, which can be calculated by Perry formula for a safer result.