With the rapid improvement of power equipment manufacturing level，sulfur hexafluoride ( SF6 ) as insulating medium for high － voltage electrical appliances is widely used in substation，which has the advantages of strong insulation and arc performance，reducing the occupied area of the equipment etc． However，leakage of SF6 gas resulting from equipment manufacturing，environment and other factors will directly affect the safe operation of high － voltage electrical appliances． SF6 gas leakage imager has high sensitivity of detection and can be used without contacting high voltage equipment directly，it is also the ideal instrument which can be used for locating the leakage points． The SF6 gas infrared imaging technology is discussed， which focuses on the relationship between SF6 gas leakage imaging and leak rate，detection distance as well as the background． Meanwhile，the field detection of SF6 gas leakage is carried out for GIS equipment in substation，which provides a reference for technical personnel．