To solve the problems of power quality comprehensive evaluation in large-scale power grid power, a new comprehensive evaluation method of the multi-target joint contribution is presented based on incentive mechanism. The evaluation process and indicators of power quality are introduced. Then, the proposed method is discussed in aspects of evaluation indicators normalization, synthetic evaluation grades, calculation, and practical test. The new comprehensive evaluation method has the special functions that highlighting the larger influence indicator, easing in calculating and suitable for the big data calculations. Finally, this method is used to the power quality comprehensive evaluation in a certain power network, and the results show its rationality and practicability.