Abstract: In order to evaluate the health status of GIS equipment, find defects as soon as possible, prevent further expansion of defects, and ensure the safe and reliable operation of equipment and power grid. This paper introduces the principle of UHF partial discharge method and AE method, the detection and joint diagnosis of GIS live equipment, and combined with the actual test case analysis of a 220 kV substation GIS, uses the electro acoustic joint method and X-ray oscillographic detection to track and locate the abnormal partial discharge signal, and verifies the correctness of the detection and analysis results.