A heat dissipating device is adapted to remove heat from an electronic package. The heat dissipating device includes a heat sink (10) and a fan (30) generating airflow. The heat sink has a base (11) and a plurality of first fins (13) extending therefrom. First airflow channels (132) are defined between the first fins. A plurality of second fins (15) are transversely attached to the first fins. The second fins have second airflow channels (152) defined therebetween. The second airflow channels communicate with the first airflow channels.