A heat dissipation device adapted for dissipating heat of a CPU and other electronic components such as MOSFETS mounted on a printed circuit board, includes a base mounted on the CPU, a fin set disposed on the base and a fan attached to a lateral side of the base and the fin set. The lateral side of the base is provided with an air-guiding part facing the fan, to guide a lower portion of airflow generated by the fan to pass through the electronic components such as MOSFETS mounted on the printed circuit board and around the CPU. An upper portion of the airflow flows through the fin set.