On the basis of theoretical analysis and the measurement on site,the temperature gradients and its variation on concrete box girder bridges resulting from ambient temperature,solar radiation and structural temperature fields were discussed.

Considering the difference of thermal expansion coefficient between carbon fiber sheet(CFS) and concrete,the equation about the thermal deformation due to solar radiation or sudden drop in temperature is established for concrete members with arbitrary cross-section strengthened by CFS.

The variation of average floor surface temperature with the average temperatures of supply and return water as well as the variation of indoor air temperature,black ball temperature and irradiance with the height are studied by means of experiments.