A position-limiting device includes a base and a position-limiting member rotatably provided on the base, the position-limiting device further includes a positioning member. The base has a hollow portion. The position-limiting member is switchable between a position-limiting state and a non-position-limiting state, when the position-limiting member is in the position-limiting state, the positioning member fixes the position of the position-limiting member; and when the position-limiting member is in the non-position-limiting state, the positioning member releases the position-limiting member, and at least a part of the position-limiting member is received in the hollow portion. The position-limiting member can switch between the position-limiting state and the non-position-limiting state, and the positioning member can fix the position of the position-limiting member and release the position-limiting member; and in the non-position-limiting state, at least a part of the position-limiting member is received in the hollow portion of the base.