Abstract: Due to the stratification of internal materials, the overall vertical temperature gradient distribution of steel-concrete composite girders is uneven, making it difficult to solve the temperature field, and the simulation accuracy and efficiency are not ideal. A general numerical model is established for one-dimensional temperature field calculation of steel-concrete composite girders based on the Fourier heat conduction law, and solved by using the successive over-relaxation iteration method. A numerical case of steel-concrete composite girder is employed to compare the calculation accuracy and efficiency between the proposed method and COMSOL. The accuracy of the method in simulating daily temperature variation and vertical temperature gradient across the entire cross-section is validated using temperature monitoring data from a large-span cable-stayed bridge, and the simulated results of the vertical temperature gradient are compared with Chinese Code for further verification. The results demonstrate that the proposed method achieves consistent calculation accuracy with that of the physical field simulation software, with 78.3% improvement in computational efficiency. Furthermore, it accurately simulates the one-dimensional temperature distribution of large-span cable-stayed bridges with steel-concrete composite girders, providing a powerful tool for calculating the temperature effects of such structures.