A heat dissipation device includes a heat sink and a pair of heat pipes fixed to the heat sink. The heat sink includes a rectangular post, four branches extending outwardly from four corners of the post, respectively, and a plurality of fins extending between the branches. Each heat pipe includes an evaporating section attached to a bottom of the post, a condensing section parallel to the evaporation section and attached to a top of the post, and an adiabatic section interconnecting the evaporating section and the condensing section. A block is secured to bottoms of the condensing sections of the heat pipes.