Abstract: This paper summarizes and analyzes an abnormal case of leakage current live detection of conventional outdoor lightning arrester and GIS built-in lightning arrester. The abnormal leakage current of the arrester is not a common quality problem such as damp aging of the valve plate of the arrester body. Combined with the relevant literature and practical work of live detection of arrester, the abnormal leakage current arrester found in this paper is a three-phase common box zinc oxide arrester for GIS equipment. This shows that the lightning arrester of GIS equipment is not perfect, and monitoring needs to be strengthened. This paper puts forward the experience of live detection of multiple arresters and suggestions on strengthening the operation, maintenance and repair of infrared thermal image detection.