A heat dissipation fan includes a rotor (1) having a hub (10) with a permanent magnet (104) attached to an inner surface thereof, a stator (2) and a fan frame (3) having a bearing seat (36). The bearing seat (36) includes a base (361) and a central tube (362) around which the stator is mounted. Slots (102) are defined through the top wall of the hub facing to the magnet ring. The base defines slots (360), corresponding to the slots of the hub.