The fan oscillating mechanism comprises a fixing support, an oscillating synchronous motor is fixedly arranged on the fixing support, and an output shaft of the oscillating synchronous motor penetrates through a shaft hole in the fixing support. The fixing support comprises a first connecting block, the oscillating synchronous motor is fixedly arranged on the first connecting block, a shaft sleeveaway from the oscillating synchronous motor is integrally formed on the first connecting block, an inner cavity of the shaft sleeve is a shaft hole, the output shaft rotationally penetrates through the shaft hole, and at least part of the output shaft is exposed out of the shaft sleeve. According to the utility model, the shaft sleeve far away from the oscillating synchronous motor is arranged onthe fixed bracket, and the output shaft is rotatably inserted into the shaft sleeve; a fulcrum can be added on the output shaft, so that the stressed swing amplitude of the output shaft is greatly reduced when the oscillating synchronous motor works, the output shaft is further ensured to rotate in a positioning manner, internal parts of the oscillating synchronous motor are prevented from beingeasily damaged, and the service life of the oscillating synchronous motor is effectively prolonged; and the stress moment of the output shaft is shortened, the swing amplitude of the output shaft is reduced, and normal work of the output shaft is ensured.