Aim To investigate the prevalence of primary aldosteronism（PA）in patients with hypertension and analyse the clinical features of confirmed PA. Methods A total of 640 consecutive outpatients with hypertension were enrolled for screening of PA.Plasma aldosterone （ALD） and plasma renin activity （PRA）were determined at 9∶30～10∶00 in the morning after the patients have been up for at least 2h and seated for 5～15 min.The radio of ALD to PRA （ARR） was calculated.Subjects with ARR ≥30 and ALD≥15 ng/dL received confirmatory Catopirl challenge test.Patients with positive results （plasma aldosterone suppressed≤30%） were dignonsed as PA.An enhancement scan was carried out in all the patients dignosed as PA for further clssification of PA subtype. Results Among 640 patients,112（17.5%）had an elevated ARR（≥30）,and 87（13.59%）had both elevated ARR（≥30）and ALD（≥15 ng/dL）.32（5%）definitely diagnosed as PA by Catopirl challenge test with the levers of ALD were suppressed less than 30% with Catopirl.20（3.125%）patients with APA underwent unilateral laparcoscopic adrenalectory,12（1.875%）patients with IHA were treated with spironolactone. Conclusion The prevalence of PA is higher in the hypertentive population,we should pay attention to hypertensive patients with PA screening.Patients with PA have typical clinical features: hypertension,hypokalemia,high urinary potassium,high aldosterone and low renin,high ARR.