The invention relates to a lubricating, cleaning or clearing device, in particular to a cleaning mechanism of a belt conveyor. The cleaning mechanism comprises a scraping plate, a scraping piece mounted on the scraping plate, and an automatic compensation structure, the automatic compensation structure comprises a sleeve, glands, a screw rod, a compression spring, a supporting spring and a connecting rod, elastic coefficient of the compression spring is larger than that of the supporting spring, the sleeve is fixed on a rack, the screw rod and the connecting rod extends into the sleeve from two ends of the sleeve respectively, the glands are arranged at the extending-in ends of the screw rod and the connecting rod respectively, the compression spring is positioned between the glands, the supporting spring externally sleeves the connecting rod, one end of the supporting spring is supported on the glands while the other end is arranged on the inner wall of the sleeve, and one end, away from the glands, of the connecting rod is connected with the scraping plate. When the cleaning mechanism is in use, the scraping piece can constantly contact with the surface of a belt, so that good cleaning effect is guaranteed.