A heat sink clip (20) includes a main body, a post (26), and a spring (27). The main body includes a longitudinal portion (31), first and second locking arms (32, 24) extending downwardly from opposite ends of the longitudinal portion. The longitudinal portion defines a through aperture (36) in a middle thereof. Two hooks (38, 46) are respectively formed at free ends of the first and second locking arms for engagement with catches (52) of a socket (52). The post has a pressing portion at a bottom thereof for being fittingly received in a blind hole (16) of a heat sink (10). The post extends through the through aperture of the longitudinal portion. The resilient element is disposed around the post below the longitudinal portion.