This paper introduces the multiple Agent system technology, which is able to automatically accomplish fault diagnosis combined with intelligent system. The technology can help the dispatcher to rapidly analyze failure causes, to accurately determine fault location and to take corresponding measures after a fault occurred in the grid. The multiple Agent system aims to calculate differential current to realize accurate identification of faulty section, combined with wide-area fault wave recording information, through using the automatic interpretation system based on knowledge reasoning and the model, and visually and uniformly display fault current of each interval and the diagnosis result on the site map. After making a judgment that faulty section is electric transmission line, the system can accurately position the location of line fault point based on double-end wave recording, zero sequence current distribution and other mature technologies. Meanwhile, supplemented by the organic coupling prudential system, recording system and SCADA system, it also can realize fault condition monitoring, fast identification of faulty section and precise positioning of fault point. After the completion of the above tasks, the engineer auxiliary analysis system is used to complete the tasks including analysis of protection behavior and its automatic archiving.