A securing device (30) is used for securing a heat sink (10) to a printed circuit board (40) with a heat-generating electronic component (41) mounted thereon. The securing device includes a V-shaped elongated main body (31), a first locking leg (34), a second locking leg (332) and a resilient member (32). The first locking leg and second locking leg are connected to two opposite ends of the main body respectively for engaging with a retention frame (20) on the printed circuit board. The resilient member includes a planar-shaped supporting plate (321) engaging with a bottom portion of the main body and at least one resilient foot (322) extending downwardly from the supporting plate. The resilient foot deforms to exert a resilient force on the heat sink when the heat sink is assembled to the electronic component by the securing device.