A heat dissipation device for dissipating heat from heat-generating components on a printed circuit board includes a cover for covering the printed circuit board and a radiator mounted on the cover. The cover defines a plurality of holes corresponding to the heat-generating components on the printed circuit board. The radiator includes a plurality of contacting portions extending through the holes of the cover for contacting the heat-generating components, respectively. The cover and the radiator are made of different materials by different manufacturing techniques, i.e. aluminum die-casting and aluminum extrusion.