Objective To study the application value of cone beam CT (CBCT) in the extraction of mandibular third impacted teeth. Methods A total of 62 patients who underwent mandibular third impacted tooth extraction in our hospital from April 2022 to February 2023 were randomly divided into control group and study group, with 31 patients in each group. The control group was examined by panoramic surface tomography, and the study group was examined by CBCT. The extraction time, postoperative recovery, incidence of complications after extraction and the root state of the third impacted tooth were compared between the two groups. Results The time of tooth extraction, the degree of postoperative pain, the duration of pain, the degree of maxillofacial swelling, the duration of swelling, the duration of postoperative bleeding and the limitation of mouth opening in the study group were better than those in the control group ( P <0.05). The incidence of complications in the study group was 6.45%, which was lower than 25.81% in the control group ( P <0.05). The coincidence rates of root bifurcation, position relationship between root and adjacent teeth, and position detection of root and neural tube in the study group were higher than those in the control group ( P <0.05). Conclusion The use of CBCT in the extraction of mandibular third impacted teeth can understand the root status of the third impacted teeth, and clarify the relationship between the third impacted teeth and the adjacent teeth and surrounding tissues. It is helpful to ensure the smooth implementation of the operation, improve the safety of the operation, and has positive significance for promoting postoperative recovery.