Some methods used in the high-voltage electrical equipment insulation fault on-line monitoring are expounded.Recent research trends and the corresponding results on carbon nanotubes gas sensor are introduced.The carbon nanotubes gas sensor is applied to monitor the characteristic gases of electrical equipment insulation fault.The components of decompositions of pure SF6

SF6/N2 gas mixtures generated by partial discharge affect on the sensor in voltage

gas pressure

temperature and other factors is highlighted.The existing problems and the future development direction of the carton nanotubes gas sensor applied in high-voltage equipment failures of on-line monitoring areas are presented.