The vibration signal is effective information reflecting the operating state of the isolating switch. In order to study the vibration characteristics of the gas insulated switchgear（GIS） under different operating conditions

a test platform with a 110 k V single-phase sub-box GIS as the main body was built. In the experiment

a variety of actual GIS operating states are simulated

and the GIS vibration signals under different currents

different filling gases

different air pressures and different contact states of the disconnector contacts are studied. The research results show that the vibration signal amplitude of the isolating switch is proportional to the square of the current. The vibration signal propagates in different filling gases

and it will be attenuated to different degrees due to the viscous absorption of the gas

moreover

the increase of the gas pressure will cause the increase of intermolecular collisions and decrease the vibration signal amplitude.After the isolation switch contacts the defect

the vibration signal amplitude decreases and the fundamental frequency increases. Based on the vibration characteristics of the GIS isolation switch under different operating conditions

the matrix similarity and the fractal box dimension are the characteristic quantities

which can well identify the contact state of the isolation switch. The research can provide a theoretical basis for the state diagnosis of GIS isolating switch based on vibration signal.