Abstract: The orthotropic steel bridge deck finite element model was established to analyze the hot spot stress． Considering the wheel loads in different vertical and lateral position，the changing process of the hot spot stress and stress amplitude were analyzed． The influence of different axle types and the most unfavorable load position were studied． It was shown that longitudinal weld at different positions had the same stress amplitude when the wheel load was moving longitudinally． The damage degree calculation result of multiaxis load was in multiple relation to that of single axle load． So，multiaxis load can be equivalent to a multiple single axle load when doing calculations． According to the analysis，the most unfavorable position along transverse direction of double wheel load is just above the weld．