In view of the problem that the existing comprehensive evaluation methods of power quality are affected by subjective factors and the evaluation models are normally complex or not accurate enough, put forward the comprehensive evaluation method based on empowerment according to the typical load classification and curvilinear unascertained function, using curvilinear unascertained function to structure the 3D unascertained measure matrix of power quality index, empower step by step, get the comprehensive evaluation index of power quality of the typical load, finally realize the grading and scoring, and then verify the accuracy and feasibility of the method by comparative analysis with the traditional linear unascertained function and grey correlation analysis evaluation methods.