Thermal expansion and cold contraction of the long busbar will cause change of mechanical state in some positions of long-busbar GIS equipment. In this study

the on-line vibration detection method was employed in vibration testing of four GIS substations in Qinghai area

where the temperature difference between day and night is large

in order to explore the vibration characteristics of long-busbar GIS equipment in large temperature difference condition. The vibration signals and their spectrum features obtained as different long-busbars worked in normal state and obvious fault state at different temperatures were compared to reveal the influence of temperature on vibration characteristics of the long-busbar GIS equipment. Analysis on a large number of vibration waveforms suggests that the large temperature difference exerts the most obvious influence on the internal poor contact fault of the long-busbar GIS equipment.