A heat sink clip (1) includes a main body (50), an operating part (30) movably received in the main body, and a pressing cam (70) pivotably attached to the main body. The main body includes a central portion (52), and two hooks (54) depending from opposite ends of the central portion. The operating part includes a driving portion (34) and a handle (32). A plurality of first teeth (346) is formed in the driving portion. The pressing cam includes a plurality of second teeth (74) that mesh with the first teeth. When the handle is slid, the first teeth drive the second teeth to rotate. The pressing cam accordingly rotates until it is forced against a top surface (3a) of a heat sink (3). The main body is thus resiliently displaced upwardly, causing the hooks to be firmly engaged with a socket (5) on which the CPU is mounted.