Thermal stress is a factor of the large bridge structure cracks which can not be ignored. As a continuous rigid frame bridge in a certain period of Guangzhou ring express way the background, using the general finite element program MIDAS/Civil, only considering the load of temperature effect established the original bridge model, reference the China road and bridge design for temperature effect on the bridge numerical analysis. By section temperature difference and system temperature change getting the stress distribution and the stress distribution of section temperature difference and the system of heating section, cooling section and the system temperature gradient linear combinations ,the stress we got will get a large section of the stress to the actual distribution of bridge crack detection have a good agreement . Cooling load combination get the Maximum tensile stress at the bridge span beam bottom and the result exceeds the tensile strength of concrete, it gets most impact to the end of the beam cracks. On the bridge design to consider the temperature effect the conclusion has some certain reference value.