Solar radiation and ambient temperature will cause deformation in a high-speed rail (HSR) bridge. Such deformation has significant effects on the structural safety and ride comfort. Based on two years' monitoring data of girder-track system on a HSR line, temperature fields for the girder and track slab could be established. Then, by using the probability statistic model asociated with the extreme value theory and an time-series analytical method, the temperature time-dependent law for the struture was studied. The study results show that the distribution of transverse temperatures on the box girder is different between the construction stage and the operation stage, due to the differential track slab's shielding effects. The temperature distribution characteristics of the box girder in different stages were obtained and different temperature calculation models were proposed. In addition, based on the annual temperature data, the temperature could be separated into uniform temperature and fluctuating temperature and the relationship between structure and shade air uniform temperatures was thus established. The concluding results may serve as a basis for the deformation control of a girder-track system.