Objective To explore the clinical application effects of cervical advancement flaps in repairing mandibular scars. Methods A retrospective analysis was performed on the clinical data of patients with mandibular scars admitted to the Department of Plastic and Burn Surgery of West China Hospital of Sichuan University between January 2018 and July 2020. The lateral X-ray images of the patients were analyzed before and 2 weeks after surgery, and the differences in the mento-cervical angles and the cervico-mental angles before and after surgery were compared. Results A total of 21 patients were included, including 7 males and 14 females. At admission, all patients had a mandibular scar area of (3-7) cm × (3-6) cm, and underwent primary repair with cervical advancement flaps. All patients had good postoperative skin flaps survival, primary wound healing, and obvious mento-cervical angle and cervico-mental angle. The preoperative mento-cervical angle was (110.24±9.47)°, and at 2 weeks post surgery, the mento-cervical angle was (98.39±4.95)°, with a statistically significant difference (P<0.05). The preoperative cervico-mental angle was (134.15±6.00)°, and at 2 weeks post surgery, the cervico-mental angle was (126.44±3.60)°, with a statistically significant difference (P<0.05). Conclusion The neck advancement flap is an effective surgical method for treating simple mandibular scar, which is simple and can improve the appearance of the jaw and neck.