A tension measurement method based on a servo constant-tension tensioner is characterized in that a revision method of the display tension value includes the following steps that firstly, a database is built, the corresponding output tension value and the measured tension value are recorded respectively, and the revision value is worked out according to the formula that the revision value=the output tension value-the measured tension value; secondly, the database is inquired, in the work state of the servo constant-tension tensioner, a line diameter is selected manually through a line diameter selection button on the servo constant-tension tensioner and then input into a single-chip microcomputer, the single-chip microcomputer continuously captures the rotation speed of a servo motor in real time when the tensioner works, and the revision value is searched for in a corresponding data table according to the line diameter and the rotation speed of the motor; and thirdly, revision is carried out, and the display tension value output by a line outlet wheel is worked out according to the formula that the display tension value=the measured tension value+the revision value and displayed on a display screen on the tensioner.