A heat sink used in an interface card includes a supporting base, a first heat-dissipating body and a second heat-dissipating body. The supporting base has a side. The first heat-dissipating body is mounted on the supporting base. The first heat-dissipating body is constituted of a plurality of overlapping heat-dissipating pieces. The heat-dissipating pieces are arranged obliquely with respect to the side. The second heat-dissipating body overlaps on the first heat-dissipating body. The second heat-dissipating body comprises a plurality of heat-dissipating pieces. Via the above arrangement, the heat-dissipating efficiency of the interface card can be increased and the lifetime thereof can be extended.