This paper describes a realizable fabrication method to manufacture chemical gas sensors by using single- walled carbon nanotubes （SWCNTs）. The sensors were tested for the monitoring of SF6 decomposition gas produced by partial discharge （PD） in GIS tank. The results showed a superior sensitivity, favorable reliability and good repro dueibitity. For further clarifying the relativity between sensor response and partial discharge activity, the discharge in GIS tank was monitored simultaneously through conventional pulse current method and a SWCNTs gas sensor, and the measurement results were put together for comparative analysis in this paper. The sensor response showed a great dependence on partial discharge characteristics. The sensor response increased nearly linearly with limits when the energy of discharge was persistently accumulated. Partial discharge power had a great influence on the response rate and the time delay. With the increase of partial discharge power, the response rate augmented almost in proportion while the time delay gradually becomes shorter with limits. The results were quite favorable to assess the partial discharge intensity and duration to some extent. Compared with pulse current method, the sensor was predominant to detect partial discharge exposed to constantly high levels of noise. It was capable of detecting partial discharge which was too weak to be detected with pulse current method. However, the sensor response didn＇t show much dependency on the apparent discharge of partial discharge.