Abstract: Elastic-plastic fracture toughness parameters of nuclear piping materials at operation temperature are of significant importance to the integrity assessment and fracture analysis based on EPFM for in-situ nuclear piping structures. Conventional elastic unloading method meets limitations at elevated temperature, while the NDRT（Normalization Data Reduction Technique） performs well without the need for simultaneous crack growth monitoring. J-R curve testing using C（T） specimens are carried out at elevated temperature in this paper. To validate the NDRT, the J-R curve at elevated temperature determined using the elastic compliance method is compared with that obtained by NDRT. The result matches each other very well, which provides a reference for researchers in the investigation of the material fracture property at elevated temperatures.