Effective evaluation methods of power quality are important to the electricity market.In this paper,thesynthesized subjective-objective weight is obtained by using the stepwise scatter degree method,and a comprehensivemodel is constructed to evaluate the power quality of regional power grids.In the investigation,first,a hierarchicaldivision of the large-scale system and the subsystems is performed according to the power quality.Next,anevaluating index system of power quality is designed and the comprehensive evaluating functions of the subsystemsand the large-scale system are established.Then,the synthesized weights of each system are determined by usingthe sequence synthesis method and the stepwise scatter degree method.Finally,the comprehensive power-qualityevaluating values of each subsystem and the large-scale system are calculated by using the comprehensive evaluatingfunctions.The proposed model helps to realize a bottom-up and multi-level comprehensive evaluation of power qualityof regional power grids and obtain comprehensive,particular and objective evaluation results.Case study on apower supply bureau shows that the proposed model is effective.