Abstract: In this paper, the factors affecting the on-site calibration of GIS UHF sensors (ultra-high frequency sensors) are studied and compared. The characteristics of propagation and attenuation of UHF signals excited by different typical flaws and steep pulse sources are compared and analyzed on the real test platform of GIS. Then, the wavelet packet analysis is used to analyze the propagation rules of signals in different frequency. Finally, combined with the status of ultra high frequency sensors of GIS on site, the validity of the experiment is tested, and some problems are found to be defective.