The utility model relates to a novel servo on -off controller, on the connecting portion of its pivot of locating servo motor and connecting axle, including the logic controller who is used for detecting motor shaft speed, the motion control device that is used for reducing servo motor shaft speed, the motion control device including the fastening locate that servo motor changes epaxial casing, first stator in locating the casing, in locating the casing the second stator, locate the casing in can near or keep away from first stator first active cell, in locating the casing near or keep away from the second active cell of second stator, be close to each other or keep away from through electromagnetic action between first stator and the first active cell, be close to each other or keep away from through electromagnetic action between second stator and the second active cell, first active cell can be connected with the connecting axle spline fit, the second active cell can with the connecting axle friction in order to increase the resistance.