A heat dissipating device includes a heat sink forming a pressing portion thereon and a clip. The heat sink includes a hollow dissipating member and a column-shaped core, and the clip includes an integrally formed body defining a round hole therein. The pressing portion extends beyond the clip and presses the body of the clip on the heat sink. The method for manufacturing the heat dissipating device as above-mentioned includes the following steps: providing a heat sink with a collar formed thereon; providing a clip on the heat sink with the collar extending beyond the clip; having the collar deformed under pressure to form a pressing portion pressing the clip on the heat sink.