The invention relates to a power prosperity index measurement method and system, and the method comprises the following steps: screening out power index data, related with the power industry, from a corresponding statistics database according to a time different correlation analysis method; obtaining a grey relational coefficient of the power index data; obtaining an independent information coefficient of the power index data according to the grey relational coefficient; obtaining an entropy value of the power index data; carrying out the standardization processing of the entropy value and the independent information coefficient, and obtaining a standard entropy value and a standard independent information coefficient; obtaining a pure information amount of the power index data according to the standard entropy value and the standard independent information coefficient; obtaining an index weight of the power index data according to the pure information amount; and obtaining a power prosperity index of the power index data according to the index weight, wherein the power prosperity index comprises a diffusion index and a synthesis index. The method can measure the reasonable and accurate weight of an important power index.