A heat duct-equipped heat-radiating device for power supply, including: a heat conductive board tightly attached to a heat source of the power supply; a heat duct tightly bridged over the heat conductive board, one end of the heat duct outward protruding from the housing of the power supply; and a fin body fixedly mounted on outer side of the housing of the power supply. The fins of the fin body are respectively formed with corresponding fitting holes through which the heat duct is fitted to contact with the fins. Accordingly, the heat generated by the heat source of the power supply is quickly conducted through the heat duct to the fin body on outer side of the housing and dissipated from the fin body to outer side.