Abstract： Objective To analyze the mechanic basis of orthodontic correction of preadolescence skeletal class Ⅲ malocclusion combined with open bite, and to summarize helpful experiences for clinical practice. Methods There were 8 preadolescent patients with severe skeletal class Ⅲ malocclusion combined with open bite [age ranged from 7 to 9 years, mean (7.9±0.8) years]. All the patients had indication of orthognathic surgery, but rejected surgical therapy. The patients received face mask traction, rapid maxillary expand, molar occlusal splint and fix appliance treatment, and were followed up for two years after the treatment. Lateral cephalometric films performed at the beginning and end of treatment were compared using traditional cephalometric analysis. Results All the patients get remarkable and stable improvement in occlusion, oral function and facial aesthetic after the treatment. The changes included the anterior movement and (5.3±1.7)° anticlockwise rotation of the maxilla (P<0.01), (2.6±0.5)° downward-backward rotation of the mandible body (P<0.01) and increase of mandible ramus length, and (5.7±0.4)° inclination of lower incisors when measured to the NB line (P<0.01). Meanwhile, the direction of the facial growth was maintained. Conclusion With the most of mechanic basis of dento-maxillofacial orthopedics, the facial growth direction of the patients with skeletal class Ⅲ malocclusion combined with open bite can be guided, and stable and esthetics curative effect can be achieved.