RESULTS: 255 men and 53 women with OSAHS aged 20～85 years were anal-ysed. Five main components were identified by PCA, which accounted for 73.091% of variance (table 1 and table 2). Four distinct clinical subtypes were identified using cluster analysis on the basis of PCA (table 3 and figure 1). Subtype1: relatively old patients with moderate OSAHS, shortest duration time of sleep apnea, had higher prevalence of comorbidities; Subtype 2: severe OSAHS patients, higher BMI, SaO2% was the lowest, had a higher arousal index; Subtype 3: you-nger patients with severe OSAHS, higher BMI, lower arousal index, lowest comorbidities, experienced more symptoms; Subtype 4: old patients, moderate OSAHS, the duration time of sleep apnea was the longest, high smoking index, minimally symptomatic patients. Importantly, patients with the same degree of AHI belonged to different subtypes, moreover, patients could manifest the similar clinical features and distributed in the same subtype, though their AHI was completely different.