A lubricating system for a fan (10) includes a lubricant storage space (17) formed at an end portion of the fan for receiving lubricant therein. A lubricant temporary retaining space (145) is defined at the other end portion of the fan for temporarily retaining the lubricant therein. A lubricant returning space (125) communicates the lubricant storage space with the lubricant temporary retaining space for enabling the lubricant to flow from the retaining space to the storage space. The returning space is defined in a tube (12) made of plastic, wherein a bearing (13) is mounted in the tube and a stator (15) is mounted around the tube.