A focusing motor an enclosure includes: a lens barrel; a lower support; an iron sheet perpendicularly fixed to the lower support; a coil attached to an inner surface of the iron sheet; at least one pair of magnets arranged on an outer side of the barrel along an optic axis of the barrel and parallel to the coil, a magnetic pole of one magnet is opposite to that of an adjacent magnet; a first guide rail disposed on the outer side of the barrel; a second guide rail disposed on an inner side of the lower support and parallel to the first guide rail; and a pulley assembly located between the barrel and the lower support, and movable along the first and second guide rails.