Abstract: The vibration signals of the running GIS equipment in 110-kV Jiangdong Gate Substation are collected and denoised. Then the denoised signals are analyzed by virtue of the Hilbert-Huang transformation(HHT). By comparing the Hilbert-Huang spectrum, the amplitude fluctuation of each frequency component with time can be obtained ; while by comparing the HHT marginal spectrum, the fault features of the GIS equipment can be retrieved. The study results show that the HHT method is very effective in analysing vibration signals and diagnosing failures for GIS equipment.