a base of a fan including a hollow shaft barrel upward extended from a central area thereof; the shaft barrel internally defining a bearing receiving hole for receiving a self-oiling bearing therein and being formed on an inner wall surface with at least one sidewall recess; and the fan including an impeller having a shaft, which is rotatably fitted in the self-oiling bearing; and

at least one oil reservoir member being correspondingly fitted in the at least one sidewall recess for storing a lubricant oil thereon; the at least one oil reservoir member also absorbing, recycling, and keeping the lubricant oil that is thrown out of the self-oiling bearing due to a centrifugal force produced by the shaft in rotating; and the lubricant oil stored in the at least one oil reservoir member being releasable to replenish the self-oiling bearing to lubricate between the self-oiling bearing and the shaft.