A cooling device for interface card for cooling a heating component on an interface card includes a heat sink and a water cooling head, wherein the heat sink has a heat conducting seat and a plurality of cooling fins. A cooling flow path is formed between any two adjacent cooling fins. In addition, the water block is attached onto the plural cooling fins of the heat sink. Thereby, the operational heat, generated from the heating element, is firstly absorbed by the heat-conducting seat and is then distributed uniformly cross to the plural fins. In addition to the heat dissipation proceeded between the fins and the ambient air, the operational heat is further conducted to the water block, undergoing a heat exchange with the coolant flowing in the water block, and thus a desired cooling effectiveness is achieved.