The invention provides a detection device and detection method for leakage of sulfur hexafluoride gas in a gas insulated switch. The detection device comprises a closed container, an adhesive, a fastening device, a detector and a to-be-detected device, wherein a detection port is formed in the upper part of the closed container and a joint opening is formed in the lower part of the closed container; the joint opening of the closed container is fixedly connected to the to-be-detected device by the fastening device; the adhesive is arranged at the fixed connecting part between the fastening device and the to-be-detected device and further the sealing of the closed container is realized; the detector is arranged at the detection port of the closed container. According to the detection deviceand the detection method provided by the invention, a plastic bag with a sticker sealing opening is designed by using a binding method and used for collecting and detecting gas leakage. The detectiondevice for the leakage of the sulfur hexafluoride gas in the gas insulated switch, provided by the invention, is matched with a common sulfur hexafluoride binding method for checking suspected leakagepoint parts, so that the detection efficiency can be greatly improved and the detection accuracy is improved.