A heat dissipation device for cooling an electronic device mounted on a printed circuited board, comprises a heat spreader contacting the electronic device, a fin assembly comprising a plurality of fins, a supporting bracket contacting the heat spreader and supporting the fin assembly, and a heat pipe extending through the fin assembly and the supporting bracket and attached to the heat spreader, wherein a lowermost fin of the fin assembly has a plurality of clasps extending near two opposite ends thereof and towards the supporting bracket. The clasps are bent to press against a bottom of the supporting bracket after the clasps extend through the supporting bracket.