A heat sink assembly includes a fixing base and a heat sink mounted on the fixing base. The fixing base has a bottom face attached to an electronic component mounted on a printed circuit board. The fixing base includes a pair of hooks extending from a rear side thereof and engaging with a support beam fixed to the printed circuit board. A pair of sleeves extend from a front side of the fixing base and two fasteners are received in the sleeves and threadedly engage with the printed circuit board. The rear and front sides of the fixing base are firmly secured to the printed circuit board, whereby the heat sink mounted on the fixing base can dissipate heat from the electronic component via the fixing base.