Objective To explore the clinical effectiveness of the lower lip cross-lip flap in repairing upper lip philtral defects. Methods Apply two types of cross-lip flaps to repair full-thickness or partial-thickness defects of the upper lip，

with the defect ranging from 1/3 to 1/2 of the entire lip， located in the philtrum area. The surgery involves one-stage transfer of the flap to repair the defect， followed by a second-stage pedicle division and trimming after the blood supply has stabilized. Results All the flaps survived without significant complications. The overall satisfaction rate for upper lip defect repair was 91.7% （including very satisfied and satisfied）. The integrity and function of the lip were good. Conclusion When the defect in the philtrum area of the upper lip reaches 1/3 to 1/2 of the entire lip， the cross-lip flap repair can be performed. The postoperative results are satisfactory， with good recovery of aesthetic appearance and lip function.

Abbe flap, Upper lip defect, Aesthetic unit of upper lip, Inferior lip artery