A heat sink assembly includes a heat sink (20) and a pair of clips (10) attached on opposite sides of the heat sink for securing the heat sink to an electronic component (40). The heat sink includes a base (22) and a plurality of fins (24). A pair of protrusions (28) is formed on bottom portions of adjacent two fins. A locking slot (29) is therefore formed between the base, the two adjacent fins, and the protrusions. The clip includes a pressing portion (12) squeenzedly received in the locking slot, a pair of extension portions (14) extending from opposite ends of the pressing portion, and a pair of hooks (16) formed on free ends of the extension portions. When the clips are deformed to cause the hooks to engage with the electronic component, the pressing portions of the clips press the heat sink toward the electronic component.