Discharge location is a key issue and technical guarantee for field AC withstand voltage test of 1100 kV Gas Insulated Metal-enclosed Switchgear (GIS). In order to ensure the smooth processing of equipment defect inspection as well as the elimination of hidden fault, the discharge location technique for AC withstand voltage test of 1100 kV GIS is studied in this research. Firstly, the process of Ultra-High Voltage (UHV) withstand voltage test is introduced. Then concerning the characteristics of the discharge in the withstand voltage test, the feature and applicability of the existing discharge location methods are analyzed. A technique for accurate discharge location by considering comprehensive multi-information is proposed according to the actual location cases. Finally, the information contained in the ultrasonic detection signal is discussed emphatically, which proves that the location based on the signal strength and the oscillation duration has higher accuracy. This research provides some reference to the subsequent UHV project construction and the equipment manufacturers. This work is supported by National Natural Science Foundation of China (No. 51221005).