Research Conclusions: The description is given to the bridge rigidity with change rates (curvature)of lateral direction , vertical direction and angle of torsion at beam ends and other locations under the design load，and the reference limit value is derived for designing rigidity of railway large-span prestressed concrete continuous beam bridge(rigid structure).With this method not only can the rigidity of simple-supported bean be described easily and conform to the existing standards，but also can the rigidities be described easily for large-span bridge and special beam structure those are not covered by the existing standards. This method and its research achievement are hopeful for improving the research and design level of bridge rigidity and providing technical support for development of larger-span bridge.