In order to study 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 models were established to verify the test. The influence of different material constitutions, simplified welding residual stress 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 and compared with the standard stability curves of various countries. The results show that both the test and the finite element model of the locally stabilized specimen have local buckling failure near the flange height of 1/2, and the larger the flange width-thickness ratio is, the earlier the specimen has local buckling failure. The finite element models are simulated by an ideal elastic-plastic constitutive model. With the increase of the relative flange width-thickness ratio, the residual stress reduces the axial stiffness of the specimen. The stability coefficient decreases by 5.4% when the flange width-thickness ratio is 30. The coefficient of stability is smallest when local initial imperfections are included. The curve of the simplified formula for the 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 curve. The trend of formula curves fitted with different steel strength is basically the same, which can be calculated by Perry formula for a safer rusult.