An object of the present invention is to provide a mechanism for disengaging a hub from an output shaft of a motor, which is convenient to propel the scooter/wheelchair manually. For this purpose, the present invention employs the following technical solution. The present invention discloses a mechanism for disengaging a hub from an output shaft of a motor; an output end of the output shaft is extended out of the motor; a coupling is fixedly sheathed on the output end of the output shaft; a hub, a movable sleeve and a compression spring are sheathed on the coupling; a stopper is fixed at an end of the output end of the output shaft; the compression spring is limited between the stopper and the movable sleeve; the hub has a central hub hole by which the hub is sheathed on the coupling; a plurality of first positioning grooves, which are arranged circularly and uniformly spaced apart from each other, are formed on an inner edge of the hub; a coupling bulge is provided in the circumference of the coupling, and a plurality of second positioning grooves, which are arranged circularly and uniformly spaced apart from each other, are formed on the coupling bulge; a plurality of first positioning bulges, which are arranged circularly and uniformly spaced apart from each other, are provided on the movable sleeve.