Crouzon s syndrome is one of the craniofacial dysostosis. It not only presents midface retrusion but also obstructs the air way. There were much more effective changes on speech and velopharyngeal function following LeFort Ⅲ maxillary advancement. In our study, 9 cases underwent maxillary advancement in the last seven years. All patients in this series underwent serial cephalometric study before and after maxillary advancement. The results showed that the distance from the posterior nasal spine to the posterior pharyngeal wall on the posterior pharyngeal wall on the lateral cephalograms reached 18.89mm which was 9.30mm more larger than that of the preoperative distance in average.The angle formed by the soft palate and the hard palate reached 159.4 degree which was 16 degree larger than the preopertive angle 144.6 degree. Clinically, improvement of phonation was very obvious.