X-rays as a special examination before orthodontic treatment play a key role in the development of a reasonable orthodontic plan. x-ray cephalometric films (ortho- and lateral films), panoramic films, and temporomandibular joint films have been taken as a routine before orthodontic treatment. In adolescents, additional hand and wrist bone films may be taken to understand whether they are at the peak of youthful growth; adult patients with suspected periodontal disease also need to take full-mouth dental films to understand the condition of the alveolar bone and periodontal membrane. X-ray cranial positioning film is divided into ortho (P-A view) and lateral view, through which orthodontists mainly observe the length, width and height of the skull and jaws, and carry out many measurements and analysis, that is, “see the essence through the phenomenon”, “deep inside” examination, in order to make a more comprehensive and reliable diagnosis, and only after that the doctor’s treatment will be well-informed. Only then will the doctor be able to make a clear-cut diagnosis and determine the correct treatment. The panorex film examines the entire set of teeth, the development of the embryo, the presence of supernumerary tooth, impacted tooth and odontoma, the eruption and position of wisdom teeth, etc. The temporomandibular joint film (TMJ film) is mainly to find out whether there are structural changes and abnormalities in the temporomandibular joint. Finally, the X-ray film is an integral part of the medical history as a legal basis, and it is always available to testify when legal matters are involved.