Abstract In order to quantitatively calibrate the characteristics of the UHF partial discharge(PD) detection technology in oil-immersed transformer, we built the common PD defects and completed the correlation experiment research in artificial imitating transformer. Meanwhile we extracted the apparent discharge magnitude and accumulated energy of PD signals as a calibration characteristic when the four defects in oil under different discharge voltage, and conducted a comparative analysis on their relationship. It is concluded that the accumulated signal energy has a linear relationship with the square of signal discharge, moreover, the goodness of fit of calibration regression curve can be influenced by the type of oil paper insulation defect and the amplitude of experiment voltage, and so the specific types and conditions of PD must be considered in UHF signal calibration. The results enrich the database of UHF detection in transformer oil and provide the favorable reference for a further study of calibrating UHF signal’s discharge quantity in oil.