The invention discloses a three-working-position electric operation mechanism for a switching device, and a driving device, a manual interlocking device and an electrical control device are arranged in a case of the mechanism, wherein the driving device adopts a single motor, a gear pair, a worm and worm gear pair, a two-way controllable overrunning clutch and an output shaft and is connected with a three-position isolation/grounding switch through a shaft coupling so as to realize the operations of closing, opening and grounding; a frame is provided with position-limiting clutch pin shafts in the closing position and the grounding position respectively, and a pair of detents, a half shaft and a tripping electromagnet are arranged in the opening position of the frame, thereby realizing the positioning for closing, opening and grounding and the mechanical clutch protection; a chain wheel transmission/bevel gear pair is used for realizing the state indication of the three positions on the front surface and the side surfaces and the position switching of a three-working-position auxiliary switch; and the manual interlocking device can realize manual-electrical interlocking and electromagnetic interlocking among switching elements. The three-working-position electric operation mechanism is simple in structure, stable in output angle, accurate in positions and unrelated to the inertia of a system, the mechanical-electrical interlocking is realized between isolation and grounding, the production and the use are safe, the reliability is very high, the cost is low, and the operations of closing a break and opening the break can be performed rapidly.