Abstract: Aiming at a steel-concrete composite box girder bridge in Wuhan area, the finite element calculation model of its temperature field is established by using the simulation analysis method of finite element software. On this basis, the temperature time history of steel-concrete composite box girder in summer is analyzed. The most unfavorable vertical temperature gradient calculated by the temperature field model is compared with the current highway bridge code in China, and the sensitivity of the main influencing factors of the vertical temperature gradient is analyzed. The results show that there is a certain temperature difference inside the steel-concrete composite box girder, and the maximum vertical daily temperature difference in summer can reach 11.2 ℃; The most unfavorable vertical temperature gradient of steel-concrete composite box girder is different from the double broken line distribution mode of highway bridge code. There is a temperature difference of 3.5 ℃ at the junction of concrete deck and steel box girder, and a temperature difference of 0.7 ℃ at the web and bottom plate of steel box girder; The influence of environmental factors on the vertical temperature gradient of steel-concrete composite box girder is greater than that of structural factors. The research results have certain theoretical value and practical significance, in order to provide reference for related projects.