The ultrasonic cleaning technology of uncoated optics with high cleanliness requirement is studied. The effects of ultrasonic cleaner,cleaning temperature,cleaning time and other parameters on optics have been carried out. An effective ultrasonic cleaning technology without damage to the surface of optics is achieved. It is found that the standing time of the optics will affect the cleanliness;the freshly polished optics has better cleanliness and shorter cleaning time.