The utility model relates to an offset filter-type ultrasonic cleaning device which is characterized by comprising a shell, a cleaning tank (3) is mounted on the inner upper portion of the shell, a water storage tank (6) is mounted on the inner lower portion of the shell, a filter screen (11) is mounted between the cleaning tank (3) and the water storage tank (6), a water spray row is mounted in the cleaning tank (3), an ultrasonic generator (4) is mounted on the outer side of the bottom of the cleaning tank (3), a bottom drain outlet (10) is mounted in the middle of the bottom of the cleaning tank (3), a bottom drain pipe (7) and a circulating water outlet (13) are respectively arranged at the bottom of the water storage tank (6), and the circulating water outlet (13) is communicated with a water supply pipeline of the water spray row through a water pump (17), so that cleaning liquid can be recycled. Tests prove that the cleaning efficiency and effects for indissolvable hard scale and heavy scale can be effectively improved by the aid of the device, so that safe operation of a power plant desulfurization system is ensured.