The present invention discloses a fan assembly for a power supply and improves the traditional installation of a fan onto a power supply that leaves insufficient spaces for designing the connecting holes as required by the existing installation specification, and mounts the fan into a power supply at a specific position by a specific fixing member and uses the fixing member to keep the fan at a specific interval from the end surface of the power supply without being in direct contact with the power supply. Therefore, the interval from the end surface provides sufficient space for the design of the ventilation holes for the airflow and the connecting holes as required by the installation specification of the power supply.