Abstract: At present, the stress of skew steel box girder in incremental launching construction is not clearly investigated. In order to obtain the structural optimization method that conforms to its stress characteristics, a three-span continuous oblique steel box girder bridge is taken as the background. Based on the numerical simulation method, the finite element full-bridge model of steel box girder is established. The stress and displacement of steel box girder under different jacking construction conditions and component parameters were extracted and compared. The variation of stress and deflection of skew steel box girder under different calculation conditions was analyzed, and the stress characteristics of skew steel box girder in jacking construction and the influence of component thickness on it was obtained. The results show that the skew steel box girder bridge presents an asymmetric stress state under the action of self-weight. The whole structure is subjected to torque, and slight rotation occurs in the vertical plane, which aggravates the local stress concentration of the structure. Increasing the thickness of the diaphragm can reduce the overall stress peak of the steel box girder by 31% and improve the asymmetric stress state. Therefore, the thickness of the diaphragm in the root area of the cantilever section can be increased in the design stage but should not be excessive.