The invention relates to a novel wall cleaning system for a building. The novel wall cleaning system comprises a bottom plate, a positioning device, a roller wheel device, a cross rod device, a scrubbing device and a water pumping device; a first supporting block and a first roller wheel are arranged on the bottom plate; a bracket device comprises a first supporting rod, a first spring, a first bracket and a second bracket; the roller wheel device comprises a first cross rod, a second supporting rod, a second cross rod, a third cross rod, a second roller wheel and a first saw tooth; the cross rod device comprises a third supporting rod, a limiting block, a second saw tooth, a fourth cross rod and a second spring; the scrubbing device comprises a moving frame, a sponge block, first brush hairs, a third bracket, a third roller wheel, second brush hairs, a first fixed rod and a third spring; the water pumping device comprises a pipeline, a water pump, a fourth spring, a fifth cross rod, a fourth bracket, a fifth spring, a water tank, a filter screen and a centralizing block. The novel wall cleaning system provided by the invention can thoroughly scrub walls and is higher in scrubbing efficiency.