A fan including an impeller structure, a rotor structure and a stator structure is disclosed. The impeller structure includes a hub and a plurality of blades disposed around the outer periphery of the hub. The rotor structure includes a shaft and a magnetic element. The shaft is disposed through the magnetic element and connected to the hub. The magnetic element includes at least one terminal surface in the axial direction, and at least one receptacle is formed on the terminal surface. The stator structure is disposed around the outer periphery of the magnetic element. The heat dissipation system and the fan thereof can improve the reliability of the motor at high rotating speed effectively and prolong the lifetime of the shaft.