【Objective】To evaluate the treatment effect of maxillary protraction on skeletal class Ⅲ high angle cases in mixed dentition.【Methods】Nine patients were treated with combined posterior occlusal acrylic and maxillary protraction.The cephalometric radiographs were analyzed before and after the treatment.【Results】The maxilla and maxillary dentitions moved forward.Overjet increased by 4.18mm (P<0.001).The anterior and posterior total face height increased.The maxilla and mandible showed no significant rotation.Profiles were improved to some extent.【Conclusion】A combined posterior occlusal acrylic and maxillary protraction can correct the sagittal maxillo-madibular interrelationships,with no unfavourable influence on facial vertical dimension.But the treatment does not change the vertical skeletal pattern.