In this research, to study the thermal behavior such as thermal stress and deformation of composite bridges with a SRC structure, a field measurement and a FE analysis were carried out for the composite trussed rohze bridge constructed by using weathering steel. In the field test, the temperatures of the surface on the bridge members were measured by an infrared camera. And then, FE analysis model was constructed by the temperature data of the field test, and FE analysis was carried out to investigate the thermal stress and deformation due to changing the thermal condition. The field test showed the value of measured temperature difference was higher than the design value. FE analysis indicated the bridge members under the dead, live and thermal load suffered under the influence of the thermal stress.