Abstract: Abstract：　Objective　To analyze the accuracy of superimposition technique of common cephalometric software Methods　A total of 80 patients treated in the Department of Orthodontics in Harbin Medical University from 2010 to 2018 were selected and divided into adolescent group and adult group, each with 40 cases. Cephalograms were taken from each sample before and after treatment. The maxillary and mandibular superimposition was analyzed by Bj?rk structural superimposition method and cephalometric software superimposition method, and the vertical and horizontal displacement and axis rotation of the landmarks of the upper and lower central incisors and the upper and lower first molars were calculated before and after orthodontic treatment. Using SPSS23.0 software, Wilcoxon signed-rank test were used to calculate whether there were differences between the two superimposition methods. Results　There were significant differences between the two methods in the vertical displacement of the upper incisors and molars in the adolescent group (P<0.05), and there was no significant difference between the two methods in the mandibular superimposition(P>0.05). There was no significant difference in the measured values of the two methods in the adult group (P>0.05). Conclusion　The analysis of the superimposition method in the cephalometric software for adolescent patients may result in inaccurate tooth movement information, so it is recommended to use the accurate Bj?rk structural superimposition method. Adult patients can use cephalometric software superimposition technique.

Key words: Key words：　cephalometric superimposition, Bj?rk structural superimposition method, cephalometric analysis, cephalometric software