Prestressed concrete bridges are exposed to solar radiation, and the surface of the structure will have a temperature difference within a certain thickness range. At the same time, the beam itself will constrain its internal fibers, resulting in temperature stress. ANSYS software is used to establish a solid element model of the main girder of a continuous rigid-frame bridge and to focus on the influence of temperature gradient. By comparing and analyzing the response of the different beam sections to the temperature stress, it is resulted that the axils between web and roof have little effect on the tensile stress caused by temperature gradient. It is proposed that the temperature stress of web has great influence on the design process of prestressed concrete bridge structure, which must be considered and can be referred for the design of the similar bridges.