Using UHF methods to carry out partial discharge detection in GIS is now one of the main partial discharge detection methods. However, PD UHF detector is biased towards the qualitative judgment of PD, and it is urgent to establish the traceability chain of detector. Referring to the electric field strength calibration methods recommend by IEEE, the essay studied the value traceability method and platform of the key factor of PD UHF detector. Sample the electric field signals in inter electrical equipment at the given frequency and convert them into electric field strength according to the relationship between indicating value and electric field strength. The experiment comparing the sample and the standard electric field strength to get the measurement error was done through the calibration platform. The measurement error of the tested product is -3.74dB~ 2.98dB. The experiment indicated the method calibrating the key factor of PD UHF detector based on transfer standard and steady-state field was feasible.