A heat dissipation device includes a retention module (60), a heat sink (10), a fan bracket (50), a fan (70) mounted on the fan bracket, and a pair of wire clips (30) cooperating with the fan bracket and the retention module to secure the heat sink to a heat-generating electronic element (82). The retention module forms a pair of fixture blocks (64) at a pair of lateral sidewalls thereof. The heat sink defines grooves (160) at lateral sides thereof. Each of the clips includes an operating portion (356) fastened to the fan bracket, a central axle (33) connecting with the operating portion and a locking portion (31) connecting with the central axle. Each central axle is slidably engaged in corresponding grooves of the heat sink and the locking portions of the clips engage with the fixture blocks of the retention module.