A self-cleaning device of a filtering net of air conditioner is installed on a filtering frame in an air inlet of a dust spiral case of a package air conditioner and is disposed outside the filtering net. A filtering net guide rail with slots is installed on an upper frame and a lower frame. The filtering net is fixed on the filtering net frame by the slots of guide rails. The cleaning device of the filtering net includes a sweeping assembly with a brush, a drive motor fixed on the sweeping assembly, a transmission mechanism connected to the drive motor, a rack group installed on the left and right side of the filtering net, a dust collecting box installed under the filtering net for collecting dust, and a dust exchanging device is disposed between the dust collecting box and the filtering net. The drive motor connected with the transmission mechanism drives the sweeping assembly sliding up and down attached the filtering net along the rack group, thus dust is cleaned by the brush, then dust is put into the dust collecting box through the dust exchanging device. The device is easily loaded and unloaded, and used with less time and labor, the filtering net can be cleaned any time or on time.