The duplex stainless stub and long columns were simulated and analyzed by establishing accurate finite element models, and the accuracy of the model was verified by experimental results. The errors between experimental values and corresponding FEM calculation results of square and round stub tubes are all less than 5%. For the long square and round columns, the errors are 2.3% and 3.8%, respectively. Upon the validation of accuracy for the FE models, systematic parametric studies were carried out. It was found that the change in mechanical properties of duplex has little influence on the bearing capacity of axial compression members. The geometric parameters of cross-section only affect the bearing capacity of the round tubes with small slenderness ratio, and the change amplitude of bearing capacity is 16%. For square tubes, the effect is more significant. Therefore, the column curves of square and round tubes were improved on the basis of the influence of relevant parameters and the strain hardening characteristics of material. The calculation formulas for the bearing capacity of square tubes and round tubes were proposed, which provides a theoretical basis for the revision of the "Technical Specifications for Stainless Steel Structures(CECS410:2015)".