The invention relates to an ultrasonic cleaning machine for cleaning residues left after laser engraving of a plastic casing of a mobile phone. The ultrasonic cleaning machine comprises a cleaning machine casing, a cleaning tank, a side piezoelectric transducer, a bottom piezoelectric transducer, a left-right direction ultrasonic generator, a front-back direction ultrasonic generator, an up-down direction ultrasonic generator, a liquid storage tank, a circulating pump, a filter, a heating pipe, a condensing pipe and a temperature controller; the cleaning tank is mounted and fixed in the cleaning machine casing; the cleaning tank comprises a bottom plate and four side plates, and the bottom plate is quadrangular, is not parallel to the horizontal plane and is inclined; the four side platesextend upward from the four edges of the bottom plate, and are not vertical but inclined; and the left-right direction ultrasonic generator and the front-back direction ultrasonic generator are connected with and control the side piezoelectric transducer, and the up-down direction ultrasonic generator is connected with and control the bottom piezoelectric transducer. According to the ultrasonic cleaning machine provided by the invention, ultrasonic sound pressure distribution is uniform during cleaning, standing waves are improved, the solution temperature is easy to control, and the cleaningeffect is good.