A heat sink assembly (100) for cooling a heat-generating electronic component, includes a base plate (32), a plurality of fins (50) mounted on the base plate and a heat pipe (20) thermally connecting the base plate and the fins. The fins are parallel to the base plate and include a bottom fin (40) supporting the fins on the base plate. The bottom fin includes a plurality of supporting tabs (422) engaging with the base plate and separating a body (42) of the bottom fin from the base plate. The bottom fin can be used not only for dissipating heat into a surrounding environment but also for reinforcing the whole strength of the heat sink assembly.