The synthetic quantified evaluation for power quality is one of the gist to weigh excellent or inferior of the power quality, and this is propitious to realize the electricity-purchase principle of discussing the price according to quality and high quality high price, thereby serve as to build the equitable electric power market. This paper proposes to use the method of matter-element for power quality evaluation, and then build the model based on the method of matter-element. Considering the non-compatible feature between the single recognition and evaluation results as well as the complexity of the evaluation for power quality, a model is approached for the evaluation of the power quality by using the matter-element and extension set. Case results show that use the proposed model is objective and reasonable, with a special advantage when used in power quality evaluation.