The invention relates to a sewage manhole cover for a water supply and drain facility and a mounting clearance cleaning machine for the sewage manhole cover. The mounting clearance cleaning machine structurally comprises a lifting column, hydraulic rods, a supporting table, bracket pillars, locking moving wheels, cleaners, mounting base brush heads, an electromagnet adsorption base, the sewage manhole cover, a manhole cover base, water spray holes and electric motors; the two sides of the upper end of the lifting column are fixedly connected with the top ends of the hydraulic rods in a weldingmanner; when the sewage manhole cover is cleaned, the mounting base brush heads are driven by the turning force of manhole cover cleaning to brush on mounting bases, the mounting base brush heads aremore stuck on the inner side surfaces of the mounting bases by means of the centrifugal force generated in rotation, and sand and stone impurities in fixed right angles of the mounting bases are cleaned completely by using the radians of the mounting base brush heads, so that when the sewage manhole cover is mounted after being cleaned, the surface is more stuck, a mounting clearance has higher sealing performance, and the condition that ascending pungent gas is blown out in sewage supply and drain to influence the life of surrounding residents is prevented.