Abstract: Objective By comparing 24 h ambulatory blood pressure levels between obstructive sleep apnea hypopnea syndrome patients combined with primary aldosteronism and without primary aldosteronism, and to understand the characteristics of the ambulatory blood pressure of OSAHS patients with PA. Methods Total 57 OSAHS patients combined with PA and 477 OSAHS patients without PA in our hospital between September, 2008 and May, 2013 were enrolled into this study. All of the patients were provided with the screening and diagnosis of PA in the standardized state, polysomnography and 24-hours ambulatory blood pressure monitoring (ABPM). Twenty-four hour ambulatory blood pressure levels of the two groups were compared. Results The average 24-h systolic blood pressure, average 24-h diastolic blood pressure and average 24-h artery pressure in the OSAHS patients with PA and the patients without PA were[(147.2±17.9) mm Hg vs. (137.7±15.4) mm Hg,1 mm Hg=0.133 kPa],[(95.7±11.5) mm Hg vs. (88.4±10.7) mm Hg], and[(112.6±13.1) mm Hg vs. (106.6±50.6) mm Hg], respectively, the difference was statistically significant (P<0.05). Conclusion 24-hours ambulatory blood pressure level in OSAHS patient combined with primary aldosteronism is higher than those without PA. We should strengthen the screening of PA in OSAHS patients to provide early correct diagnosis and treatment for the special secondary hypertension patients.