Objective: To obtain orthodontic force which is the most suitable for mandibular 3-7 group-teeth malor distalization by finite element method analysis; observe and compare the distalization condition of mandibular second molar during pushing single-tooth malor distalization and group-teeth malor distalization for guiding clinics; Method: spiral CT was adopted for maxillofacial region CT scanning on one individual normal jaw patient, mimics, Geomagic Studio and Abaqus software were combined to establish two groups of finite element models, namely model I of microimplant anchorage between mandibular first and second molars, and model II of micro-implant anchorage in mandibular external obilque line, and all models underwent stress application and calculation. Results: 1. When 150g horizontal force was used to push mandibular second molar for malor distalization, the movement mode of the tooth is inclination movement accompanied with lingual reverse, and the tooth also suffered from tongue inclination and elongation during malor distalization; 2. When implants were embedded into external obilque line zone for group-teeth malor distalization, and the movement mode of mandibular second molar was similar to integral movement; 3. Too large force value was not beneficial for tooth movement, and the most suitable orthodontic force for 3-7 group-teeth malor distalization is 250g. Conclusion: group-teeth malor distalization is more beneficial for tooth integral movement, 250g is the the most suitable orthodontic force for group-teeth malor distalization.