Abstract: The stress influence function for pipe under high temperature and high pressure was developed based on Green function, and its reasonability was validated using high temperature strain measurement through special experiment. The result indicates that the stress obtained by the simplified method of stress calculation is well coincident with experimental measured result. The simplified method of stress calculation is one of the effective ways of rapid assessment for strengthen and fatigue life of critical component and pipe for nuclear power plant. Furthermore, the method can also be used for fatigue monitoring system development.