Objective To explore the effect of self-ligating bracket non-extraction orthodontics on apical root resorption and treatment time in patients with severe crowding in permanent dentition. Methods A total of 80 patients with severe crowding in permanent dentition admitted to Jianshi County Hospital of Traditional Chinese Medicine from May 2024 to May 2025 were selected as the research subjects, and they were divided into the traditional group and the self-ligating group by the random number table method, with 40 patients in each group. The traditional group received extraction orthodontics with traditional OPA-K straight wire bracket system, and the self-ligating group received self-ligating bracket non-extraction orthodontics. The root length, apical root resorption and treatment time were compared between the two groups. Results The root lengths of maxillary central incisors, maxillary lateral incisors, mandibular central incisors and mandibular lateral incisors in the self-ligating group at 1 month after orthodontics were higher than those in the traditional group (P<0.05). The apical root resorption in the self-ligating group at 1 month after orthodontics was better than that in the traditional group (P<0.05). The overall course of treatment, dentition alignment time and space closure time in the self-ligating group were shorter than those in the traditional group (P<0.05). Conclusion For the treatment of severe crowding in permanent dentition, self-ligating bracket non-extraction orthodontics can not only improve treatment efffciency and shorten treatment time, but also better protect the root, effectively reduce the degree of root resorption and lower the risk of severe resorption.