The gas detector includes sulfur hexafluoride detection unit, oxygen detection unit, temperature and humidity measurement unit and communication unit. The detection of sulfur hexafluoride adopts infrared detection technology, which overcomes the shortcomings of large measurement error, poor accuracy, and poor stability; oxygen The detection unit adopts German imported sensors with high measurement accuracy and stable performance; the temperature and humidity measurement part adopts a digital output temperature and humidity module, which has the characteristics of high accuracy and good repeatability. In summary, the gas detector can monitor the SF6 gas concentration, oxygen content, and temperature and humidity changes in the environment in real time and online, and upload the detected data through the RS-485 bus