An exemplary cooling fan includes a base, a central tube formed at the base, a stator, and a rotor being rotatable relative to the stator. The central tube is made of polyoxymethylene. The central tube includes a bottom plate mounted on the base and a peripheral sidewall extending upwardly from a peripheral edges of the bottom plate. The bottom plate and the sidewall cooperatively define a blind hole therebetween. The stator is mounted around the sidewall of the central tube. The rotor includes a hub and a shaft extending from the hub. The shaft includes a free end received in the blind hole and directly abutting the bottom plate.