It has been said that the development of dentistry is the development of dental materials science. It is so, with the development of material science and technology, the level of orthodontics is also developing by leaps and bounds. After working in the clinic for many years and constantly learning and exchanging new techniques around the country, we finally figured out a method that can correct partial malocclusion without extracting teeth. It consists of three parts: 1, arch expander. In the past, the clinically used movable arch expander was very uncomfortable for patients to wear, and not many of them cooperated, so the effect was very unsatisfactory. Now we can use fixed casting arch expander, which is comfortable for patients to wear and the effect is very reliable. 2.Push the molar backward device. It has always been a difficult step for the clinician to push the teeth backwards. The various devices used are also difficult for patients to tolerate. For this reason, the author invented a simple and effective device for pushing the molar backward after continuous clinical exploration and experimentation, which is very effective clinically and does not require additional cost. 3.Self-locking brackets. If the first two devices together with self-locking bracket effect is better. Of course, not all malocclusion can be done without extraction, it needs to have certain indications. For example, the age of 15 years old or less, preferably the second molar has not yet erupted, etc.