Aiming at the damage phenomena of length standard in ultrasonic cleaning process, the factors influencing the ultrasonic cavitation erosion effect are studied. According to RayleighPlesset equation, the evolution curve of bubble radius is solved, and the maximum temperature and normal stress response in the bubble for the first collapse of the cavitation bubble under different initial radius, frequency and temperature of the gas nucleus are obtained, and then the damage reason of the length standard is analyzed. A new method of deterioration is proposed to study the effects of ultrasonic frequency, temperature and ultrasonic radiation time on the decontamination effects and corrosion stages of the length standard. The experiment results show that the cleaning process of the length standard is divided into three stages: cavitation cleaning stage, cavitation erosion incubation stage and cavitation erosion acceleration stage. In the process of removing oil pollution, the effect of cavitation erosion is very small. When the solution temperature is 60℃, the ultrasonic frequency is 28 kHz and the radiation time is 1 minute, the cleaning effect will be better.