Abstract: The relative calibration method of AXUV photodiodes used on the nuclear fusion Tokamak EAST and HT-7 was given. These photodiodes were used for absolute radiated power measurement. The changes of the detector surface were usually observed after one experiment campaign. Five sensors suffered different plasma discharge irradiations were compared by relative calibration. The X-ray tube and standard light source were chosen as the calibration source. The results show that the detector response can decrease 15% after 25 000 discharge irradiation accumulations. The response changes between channels in one photodiode array were observed. The cumulative irradiation doses were evaluated according to the geometry parameter of the detector in radiation field.