Abstract: The ultrasonic cavitation behavior of ZL101 cast aluminum alloy at amplitudes of 60, 70 and 80 μm was studied by ultrasonic vibration cavitation device. The results show that ZL101 cast aluminum alloy was mainly composed of Al phase and a small amount of Fe and Al_0.5Fe₃Si_0.5 phases. Under the repeated impact and collapse of cavitation, the softer Al phase inside the grain was first destroyed by cavitation erosion. In turn, the grain boundaries were lost to produce small cavitation pits. Under different amplitudes, the cavitation surface produced obvious plastic deformation and brittle fracture, and had obvious punching and hollowing behaviors. The increase of the amplitude led to the increase of the ultrasonic intensity and the maximum sound pressure, which in turn led to the increase of the pressure fluctuation in the cavitation environment and the increase of cavitation collapse, which intensified the cavitation damage of the ZL101 cast aluminum alloy and increased the cavitation quality loss and the pit depth.