The invention discloses a cleaning device for fan blades of a fan. The cleaning device comprises racks and a base which is fixedly mounted at the lower ends inside the two racks, wherein the middle parts of the inner side surfaces of the racks are equipped with an ultrasonic emitter and a settling tank; a water storage box is arranged on the side surface of the ultrasonic generator; a water pump is arranged in the water storage box; a water inlet is formed in the upper end of the side surface of the settling tank; a cleaning slot is formed in the upper ends of the inner side surfaces of the racks; a water draining tube is arranged between the cleaning slot and the settling tank; a water pumping tube is arranged between the cleaning slot and the water storage box; a wiring tube is arranged between the cleaning slot and the ultrasonic generator; and the ultrasonic generator is electrically connected with an ultrasonic transducer. The cleaning device for fan blades of the fan disclosed by the invention has the beneficial effects that: the cleaning device for fan blades of the fan can realize automatically cleaning a mesh enclosure and fan blades of the fan, does not need to dismount and manual wiping, saves time and labor, is good in wiping effect, is simple and convenient to operate, and is high in practicability.