A clip assembly (30) for mounting a heat sink (20) on a printed circuit board (10) includes a closed annular positioning portion (32) interferingly engaging with the heat sink, a securing portion (34) secured to the positioning portion. The securing portion has a pressing member (340) extending through an opening (320) defined in the positioning portion for resiliently abutting against the heat sink, and two arms (344) extending from free ends of the pressing member with a pair of hooks (342) formed at distal portions of the two arms for engaging with the printed circuit board.