The need for orthodontic extraction is determined by many factors and requires the patient to undergo an examination at a regular hospital, including a general examination of the oral cavity and the acquisition of surface tomograms, cephalometric radiographs, census models, and in some cases, dental CT films. The cognitive model is an accurate reproduction of the patient’s teeth, arch, alveolar, basal bone, palatal capping and the relationship between the upper and lower jaws. The surgeon will analyze the model for measurements and decide whether to extract the teeth in combination with surface tomograms and cephalometric radiographs, etc. In simple crowding, the malocclusion involves only the teeth and alveolar bone, the purpose of extraction is mainly to solve the crowding, and the extraction or not is mainly based on the severity of the crowding. Generally speaking, mild crowding can be avoided by the method of arch expansion or adjacent surface de-enamelization, while severe crowding can only be achieved by extracting teeth to obtain enough space to align and level the arch; moderate crowding is mostly a marginal case that can be extracted or not, which requires high clinical experience of the doctor. The treatment plan should be decided after a comprehensive measurement and analysis of the patient’s dental and maxillofacial hard and soft tissue morphology, and the principle is not to extract teeth when possible.