Aluminum foil erosion was used to measure the distribution of the ultrasonic field in both bath and probe sonoreactors under varied sonication conditions, to explore the ultrasonic cavitation mechanism and to clarify the impact of sonication conditions on cavitation effect. Two-dimension ultrasonic cavitation field was visualized based on Matlab software. Then it was analyzed and verified through ultrasonic experimental. The distribution of ultrasonic cavitation field in bath sonoreactor was uneven. In addition, the erosion areas decreased with the increasing of ultrasonic frequency, accompanying a worse cavitation effect. The strongest cavitation effect occurred at the antinode, which responded to the largest effective areas. As to the probe sonoreactor, the effective areas were mainly distributed in the vicinity of the axis of the probe. The cavitation effect gradually became weakened while the inefficient areas increased when the distance between aluminum foil and probe became further. The increasing of ultrasonic density contributed to a stronger cavitation effect, the erosion areas could reach up to 80% at 5W/mL. It was also indicated that under the same conditions, ultrasonic cavitation effect in bath sonoreactor was stronger compared to the probe one. The increase of ultrasonic density led to the enhancement of the concentration of soluble chemical oxygen demand (SCOD), indicating well sludge disintegration effect. The disintegration of sludge and cavitation effect decreased as the ultrasonic frequency increased.