〔Abstract〕 Objective To investigate the application effect of orthodontic tooth separation technique in the treatment of early adjacent surface caries with compound resin filling. Methods A total of 104 patients with early adjacent surface caries were selected from Henan Saisi Dental Hospital from December 2019 to November 2020 were divided into a control group and an observation group by computer random number table method, with 52 cases in each group. The control group was treated with conventional composite resin filling, and the observation group was treated with orthodontic dental separation for early adjacent surface caries. Patients in the two groups were followed up in the outpatient clinic for 6 months after the operation, and the success rate of filling, the appearance of filling, and oral health-related quality of life (OHRQOL-UK) scores before and 6 months after the operation were compared. Results The filling body integrity in the observation group was better than that in the control group (Z = 11.266, P = 0.004), and the edge coloring was also better than that in the control group (Z = 8.421, P = 0.015). The filling success rate of the observation group was 94.23%, higher than 78.85% of the control group, and the difference was statistically significant (P < 0.05). 6 months after surgery, OHRQOL-UK scores were significantly improved in the two groups, and OHRQOL-UK score of the observation group was higher than that of the control group, with statistically significant differences (P < 0.05). Conclusion The application of orthodontic tooth separation technique in the treatment of early adjacent surface caries compound resin filling can improve the success rate of filling, ensure good appearance of filling and improve the oral health quality of life of patients