Objective: To explore the best cut-off point of orthostatic plasma aldosterone/plasma renin concentration (ADRR) for screening primary aldosteronism (PA). Methods: 80 cases of patients with unknown causes of hypertension were divided into PA group (combined with PA, n=20) and primary hypertension group (hypertension group, not combined with PA, n=60). The body height, body weight, blood pressure, blood potassium, orthostatic plasma aldosterone concentration (PAC), plasma renin activity (PRA) and plasma direct renin concentration (PDC) were measured respectively of all the patients; And the PAC/PRA (ARR) and ADRR were calculated. The ROC curve was drawn to determine the best cut-off point of orthostatic ADRR screening for PA. Results: The serum potassium level, PDC and PRA of patients in PA group were significantly lower than hypertension group, while the PAC, ADRR and ARR were significantly higher than hypertension group (P<0.05). The area under ROC curve of ARR was 0.698, and the diagnostic cut-off for screening PA was 63.77 [(pg/ml)/(μg/L/h)]. The area under ROC curve of ADRR was 0.882, and the diagnostic cut-off for screening PA was 2.55 (pg/ml)/(pg/ml). Conclusions: The diagnostic value of ADRR screening for PA is higher than that of ARR. It is suggested that ADRR can be used in clinical screening for PA.