The invention provides a method and a device for visual evaluation of the accuracy of an electronic sphygmomanometer based on Korotkoff Sound. The method comprises the following steps: measuring the blood pressure of a subject by the Korotkoff Sound method, recording sound signals from the stethoscope during the measurement, recording changes in the pressure of the cuff by using a pressure sensor during the measurement, converting the recorded pressure and sound signals into digital signals, sending the digital signals to a computer that processes the digital signals and displays, respectively on a display screen, the wave patterns of the cuff pressure signal and the stethoscope sound signal that vary synchronously along the same timeline, calibrating and verifying systolic pressure value and diastolic pressure value measured by the Korotkoff Sound method according to the wave patterns, and using the values as references for accuracy evaluation of blood pressure measured by the electronic sphygmomanometer. The systolic pressure value and the diastolic pressure value are determined more accurately and objectively based on the visual Korotkoff Sound method of the invention, which minimizes the error caused by manual measurement of blood pressure, and improves the accuracy and objectivity of the whole evaluation system.