The current predominant method for partial discharge (PD) localization necessitates manual measurements of the distances between sensors and time-of-arrival differences by maintenance personnel. To enhance the intelligence of automatic localization techniques, this paper conducted research on PD localization within Gas-Insulated Switchgear (GIS) using digital twin technology. We propose an automatic PD localization technique for GIS based on digital twins. Initially, we establish a digital twin model of a typical GIS, compute the shortest distances between any two points within the model, thus creating a “time delay fingerprint database.” Using this database in conjunction with the time-of-arrival difference method allows for the automatic localization of partial discharges. The effectiveness of this algorithm has been verified through simulation experiments.