Abstract: An experimental study on ultrasonic cleaning of optics was carried out. Optimization of the cleaning process was performed through comparative experiments with different cleaning reagents and temperatures. The optimized cleaning process removes both organic pollutants and inorganic pollutants effectively. After optimized cleaning, the optics surface shows no additional damage, with the contact angle less than 6, and no pollutant particles larger than 1 m left. Ultrasonic cleaning attains a better cleaning effect than manual cleaning.