The present application discloses a locking device including: a mounting seat; a locking member, rotatable around an axial direction and movable in the axial direction, when the locking member is in a first axial position and a first rotational position, the locking member is retracted into the mounting seat along the axial direction, and the mounting seat prevents the locking member from rotating around the axial direction; and when the locking member is in a second axial position and a second rotational position, at least a portion of the locking member extends in the axial direction from the mounting seat, to be inserted into and engaged with a second object, and the mounting seat prevents the locking member from moving in the axial direction; and a compression torsional spring biasing the locking member toward the first axial position and the second rotational position.