Abstract: Objective To compare the differences of automated office blood pressure（AOBP） and blood pressure values measured by other methods, and to explore the cut-off point of AOBP for diagnosing hypertension. Methods From September 2017 to January 2020, 206 patients with untreated essential hypertension in the outpatient department of cardiovascular of the First Affiliated Hospital of Fujian Medical University were enrolled. Clinical data were collected and biochemical indexes were detected. The office blood pressure（OBP）, AOBP, home blood pressure（HBP） and 24-hour ambulatory blood pressure（ABP） were measured in all subjects. According to 2017 Canadian Hypertension Education Program（CHEP）, patients with hypertension were divided into two groups: AOBP increased group（≥135/85 mmHg） and AOBP normal group（＜135/85 mmHg）. The difference of blood pressure values was compared by variance analysis of repeated measurement and the correlation was analysed by Pearson correlation analysis. The receiver operating characteristic（ROC） curve was used to identify the cut-off point of AOBP for diagnosing hypertension, using daytime ambulatory blood pressure（dABP） as the diagnostic standard. Results In patients with hypertension, the blood pressure values were ranked in descending order as follows: OBP＞AOBP＞dABP＞HBP. AOBP was highly correlated with OBP when AOBP≥135/85 mmHg（r=0.768 for systolic blood pressure, r=0.705 for diastolic blood pressure, both P＜0.05）, and had the highest correlation with dABP（r=0.424 for systolic blood pressure, r=0.495 for diastolic blood pressure, both P＜0.01） when AOBP＜135/85 mmHg. The best cut-off point of AOBP in diagnosing hypertension was 133.5/82.5 mmHg, with a sensitivity of 88.1%, and a specificity of 64.8%. Conclusions Of untreated hypertension patients, OBP＞AOBP＞dABP＞HBP. The cut-off point of AOBP for hypertension diagnosis is 133.5/82.5 mmHg.