A heat sink assembly (100) includes a heat sink (10) having a plurality of fins (14), a fan handle (24) buckled with the fins and a fan (30) mounted on the heat sink (10) via the fan handle. The fan handle includes a retaining body (26) clasping two adjacent fins having a space therebetween. A screw (22) is extended through the fan and into the space of the two adjacent fins. The retaining body includes a pair of opposite lateral walls (260) clamping opposite sides of the two adjacent fins, for preventing the two adjacent fins from being over expanded outwardly during the insertion of the screw into the space.