The utility model provides a motor is stator clamping device for assembly machine, frame actuating mechanism including stator clamping rack, the reciprocal linear motion of drive stator clamping rack, be equipped with fixed cover seat, movable sleeve seat and the fixed cover seat reciprocating motion's of drive movable sleeve orientation cover seat actuating mechanism on the stator clamping rack, frame actuating mechanism includes frame driving motor, transmission lead screw, screw -nut and guide rail, frame and screw -nut fixed connection, frame bottom be equipped with with guide rail complex slider, cover seat actuating mechanism drives actuating cylinder including the cover seat, the piston rod terminus that the cover seat drove actuating cylinder is connected with the movable sleeve seat, the movable sleeve seat slides and locates on the guide rail, the movable sleeve seat upward corresponds the position with fixed cover seat and is equipped with the logical groove with outer diameter of the stator matched with, it locates a plurality of holders to be equipped with the ring between movable sleeve seat and the fixed cover seat. The utility model discloses the centre gripping synchronism is better with stability, and the centre gripping is reliable and stable.