Abstract: An improved combination weighting radar chart method is provided and applied to the synthetic evaluation of power quality. The probability theory and mathematical statistics methods are used for processing the weight of index,which is decided by the subjective or objective weighting method. The optimization model is established based on minimizing the total deviations between each original evaluation weight and the combination weight. In the improved combination weighting radar chart,the sector area is ranked and the angle of the sector area is distributed by the weighting. The diagonal of sector area is employed by using the radar chart as index axes. The combination weighting radar chart method can not only focus on the importance degree of different evaluation indexes,but also reflect the interaction. Verification results verify the reliability and validity of the method.