The invention discloses a high-efficiency grinding device for building decorative walls, which comprises a bottom plate, a first support leg, a roller, a first support plate, a second support leg, a T-shaped slider, a support shaft, a second motor, a threaded rod, a first Two support plates, the first box body, the second box body, the transmission mechanism, the second box body, the support rod, the fourth motor, the grinding fan and the dust removal device, the present invention is provided with the third motor, the threaded rod and the second support plate , adjust the height of the whole device through the cooperation of the above components, so as to grind the different heights of the wall surface. There is a transmission mechanism, which drives the grinding fan to rotate and move up and down through the transmission mechanism, so as to polish the building wall surface, which is convenient and fast. The one with high efficiency is equipped with a dust removal device. The dust removal device includes a connecting rod, a suction nozzle and a vacuum cleaner to remove a large amount of dust generated during the grinding process, so as to avoid affecting the health of the decorator and increasing the difficulty of cleaning later.