Cocoon brushing is a vitally important process in silk reeling, it closely relates to raw silk quality and reeling efficiency. In this research, an ultrasonic-assisted cocoon brushing process is proposed, which can achieve cocoon reeling and silk cleaning at lower temperature and alleviate the problem of using excessive temperature to cocoon brushing in silk reeling factories. The cocoon brushing effect of different treatment conditions is investigated by fuzzy orthogonal method to obtain the optimal process: ultrasonic temperature 80 °C, ultrasonic time 40 s, ultrasonic power 144 W, cocoon cooking time 3 min. Compared with the conventional process, the total number of cocoon brushing is reduced by 4.75 times, the reelability percentage is heightened 11.39% and the rushing upon cocoons per myriameter is lessened 2.53 times. After ultrasonic treatment, the secondary structure and thermal stability of raw silk are not change. The sericin distribution is more uniform and the mechanical properties are improved to a certain extent. The temperature of this process is about 15 °C lower than the silk reeling factory and it can save 93 MJ for 1 kg of raw silk per reeling. Results show that ultrasonic can be used to develop an green process for cocoon brushing, which may provide a technical reference for the silk environmental protection production.