Heat dissipation device and fan assembly thereof

A heat dissipation device comprising:

• a heat sink;
• a cooling fan mounted on the heat sink for providing a forced airflow towards the heat sink, the cooling fan comprising a fan housing and an impeller received in the fan housing, the impeller comprising a hub and a plurality of fan blades extending radially from the hub, a shaft extending from the hub and having a distal end protruded out of the fan housing, a fan pulley arranged around the distal end of the shaft;
• an electric motor comprising a driving pulley corresponding to the fan pulley of the cooling fan;
• and
• a belt having one end engaging with the driving pulley of the electric motor and an opposite end engaging with the fan pulley of the cooling fan for associating the electric motor with the shaft of the impeller of the cooling fan, rotation of the driving pulley of the electric motor being transferred to the fan pulley via the belt to cause the impeller of the cooling fan to rotate.