The invention relates to a tristable differential permanent magnetic operating mechanism, which is suitable to be used in automatic transfer switch equipment. The mechanism mainly comprises a main power closing coil, a standby power closing coil, a main power auxiliary opening coil, a standby power auxiliary opening coil, a tristable maintaining spring, a movable core, a drive rod, a permanent magnet and a magnetic block. The drive rod of the tristable differential permanent magnetic operating mechanism can be stabilized in three positions, and one or a plurality of load circuits can be reliably transferred from one power supply to another power supply without needing to increase a mechanical and electrical interlocking device. The mechanism has the advantages of simple structure, high reliability and good controllability, and is an idea component for developing integrated ATSE (Automatic Transfer Switch Equipment).