The invention discloses a power grid transmission quality evaluation method based on phase compensation amplitude subtraction, and belongs to the field of electric systems and the like. The method comprises the steps that firstly, the phase angle range of each section is calculated at first, a zone bit generator, a first time recorder and a first mutual inductor are made to work synchronously, a controller obtains original phase information of power plant signals through differential output, the section where the original phase of the power plant signals is located is calculated, the time difference is recorded according to two time recorders, output signals of a second mutual inductor are adjusted, the controller judges whether the third comparison output is positive or negative, sectioncompensation parameters are calculated according to a table lookup mode on the basis of subtraction rules, then, the controller judges whether the first comparison output, the second comparison outputand the third comparison output are positive or negative, the section of the phase obtained after the power plant signals are transmitted through a power grid is calculated, and finally the power grid transmission quality is judged according to the continuous sections,; the method can be used for power grid transmission quality evaluation, and the problem of erroneous judgment caused by time delay is solved.