This paper proposed to adopt a method called Equivalent Pulse Injection（EPI）to fix the criterion and conducted an investigation into the consistency of UHF signals produced by the GIS PD and the process of EPI. By measuring the waveforms of electromagnetic waves of EPI and real GIS PD

it is found that the pulse signals waveforms coupled by the UHF sensor are accordant. Under the same research conditions

the signal attenuation characteristic of real PD and the EPI injection show high consistency and they have a same available measure range. The research results show that EPI method and real PD signal measure are very consistent

so the EPI can be adopted to fix the criterion of UHF signal on-line monitoring of GIS PD on the spot.