Obstructive sleep apnea(OSA)is a common type of sleep disorder characterized by abnormal repetitive cessation in breathing during sleep caused by partial or complete narrowing of pharynx.In this study,the large eddy simulation(LES)approach is used to investigate the inspiratory and expiratory airflow characteristics in the human upper airway for the purpose of identifying the probable locations of illness.The human upper airway was reconstructed based on CT scan data.During 30 L/min respiration,the airflow characteristics in unique sections were explored at the peak of inspiration and expiration.The injection phenomenon caused by narrowing of pharynx was discussed based on the distribution of instantaneous velocity and static pressure in typical points.At last,the distribution of temporal velocity and static pressure were also studied in different respiration intensity.The present results would provide theoretical guidance for the treatment of respiratory disease.