Abstract: Objective: To observe whether ultrasound could accelerate tooth movement in a rat orthodontic model. Methods: In this study, 30 rats were randomly divided into 2 groups, with 5 rats at each time point. Orthodontic appliances were placed between the maxillary first molars and central incisors. The rats were randomly divided into 2 groups: group 1 was normal treatment and group 2 was ultrasound treatment. The rats were sacrificed at different time points (t=7, 14, 28 days), the distances of tooth movement were measured and histologically observed. Results: The ultrasound significantly increased orthodontics tooth movement distances at day 7, 14, 28 compared with conventional orthodontic group. Histological observation demonstrated that the count of osteoclasts in the experimental group was significantly more than that in the conventional orthodontic group. Via Masson staining, new bone formation was found in both groups at the 7th day; after 14 days, there were more new bone formation in the group 1; 28 days later, more new bone formation was found in the group 2. Conclusion: The results suggest that the ultrasound can significantly increase the osteoclastogenesis around the moving tooth. This effect may induce the accelerated tooth movement.