Abstract: Objective To detect whether the blood pressure（BP） measured with an automatic arm sphygmomanometer in the waiting room should be used as the office BP or the out-of-office BP. Methods A total of 238 subjects in the outpatient Department of Cardiovascular Medicine of the Second Affiliated Hospital of Nanchang University from from August 20th to September 22nd, 2023 with an average age of（55.0±15.3） years were included. Two automatic arm sphygmomanometers（HBP-9021） were used, one in the waiting room and the other in the office. All participants were trained to use an automatic arm sphygmomanometer prior to BP measurement, and BP measurement in the waiting room was done entirely by the patient themselves. The order of BP measurements in the office and waiting room was determined using a random crossover method. The BP of the right upper arm was measured twice in each occasion, with an interval of 1 minute, and the mean value was taken as the final value, and the difference of BP and heart rate between the consultation room and waiting room was analyzed. Results Compared with the data from the waiting room, the systolic BP（SBP） in the office was significantly higher （138.1±20.1） vs（133.0±20.9） mmHg, t=8.965, P＜0.01, with an increase of（5.1±8.8） mmHg, and the diastolic BP（DBP） in the office was also significantly higher （78.7±13.4） vs（76.4±13.7） mmHg, t=5.487, P＜0.01, with an increase of（2.3±6.5） mmHg. In 123 hypertensive patients, SBP in the office increased by（4.3±9.0） mmHg（P＜0.01）, and DBP in the office increased by（1.7±7.1） mmHg（P＜0.01）. More than 70% of patients’ SBP and DBP were higher than those in the waiting room. Conclusion Using the same type of arm-type sphygmomanometer to measure blood pressure, the SBP and DBP measured in the waiting room are lower than those in the clinic, so the BP data in the waiting room should not be used as the BP data in the clinic.