A heat dissipation device includes a heat spreader (100), a fin assembly (300) located above the heat spreader and a heat pipe (400). The heat spreader has a bottom (110) for contacting a heat-generating component (500) and an upper surface (120) with a groove (122) defined therein. The fin assembly includes a plurality of horizontal fins stacked on each other. The heat pipe includes a first section (410) accommodated in the groove of the heat spreader, a pair of first legs (422) extending from opposite ends of the first section, respectively, and away from the heat spreader, and a second leg (424) bent from each of the first legs towards the heat spreader. The first and second legs pass through the horizontal fins and are fixed to and thermally connected with the horizontal fins.