The causes of lip ectropion are: i. Due to the protrusion of the upper jaw and lip ectropion caused by mouth breathing, patients who breathe through the mouth mostly have poor ventilation of the respiratory airway, such as those suffering from chronic rhinitis, sinusitis, twisted nasal septum, adenoid hypertrophy and other diseases, forcing the use of mouth breathing, the airflow passes through the upper jaw of the mouth for a long time, causing the upper jaw to protrude, the front teeth to ectropion, and the lips to ectropion; ii. Due to the tongue habitually licking the front teeth, Bad habits such as biting hard objects and sucking fingertips lead to the outward turning and twisting deformity of the front teeth, so that the lips are turned out and cannot be closed naturally; third, the lips are suddenly swollen and turned out because of allergy and angioneurotic edema of the lips; fourth, trauma also makes the lips swollen and turned out; fifth, long-term ulceration and erosion of the inner mucosa of the lips also makes the lips red and swollen and turned out.