An injection mold for molding a lens barrel is disclosed. The injection mold includes a female die, a male die and a screw die. The female die and the male die are correspondingly connected to two ends of the screw die. The female die, the male die and the screw die cooperatively define a mold cavity. The female die includes a female die plate and a female die core protruding from the female die plate. The male die includes a male die plate and a male die core protruding from the male die plate. The male die defines a through hole passing through the male die plate and the male die core. An air gap is formed between the distal ends of female die core and the male die core, the air gap is communicated with the mold cavity and the through hole.