Objective: To explore the operation method and clinical effect of treatment for bilateral cleft lip with improved straight line closure. Methods: On the basis of straight line closure, the vermilion and anterior lip pear were repaired with the muscle-vermilion labial flap of lateral lip. In order to close nasal floor, flap-C from lateral wall of anterior lip and flap-G from nasal wing base were designed, meanwhile, nasal mucosa flap-D and flap-H from two sides of nasal base fissure were designed. The function of the orbicularis oris was repaired by cutting off the anomaly adhesion of the orbicularis oris. Results: The post-operational upper lip was thickened together with good shape and vermilion color, there was no obvious dynamic abnormality, nasal floor was closed well. Conclusion: The improved straight line closure can obtain good shape of lip, reduce the whistling deformities, oronasal fistula and dynamic abnormality.