Abstract: Objective To study the clinical characteristics of patients with obstructive sleep apnea syndrome（OSAHS）.Methods PSG monitoring data about 90 patients with OSAHS were analyzed.Results The age,body weight,maximum time of apnea,and minimum arterial oxygen saturation were significantly different in patients with mild,moderate,and severe OSAHS（P＜0.05）.Conclusion Obesity is an important risk factor for OSAHS.Apnea,hypoventilation time and declined S_pO₂% can also be used as the indicators for the severity of OSAHS.