For the currently available evaluation indices of open， fair， and just power dispatching， attention is paid only to the final results of the annual power generation plan， to the neglect of the execution process. This may cause profit inequity among generation enterprises and affect the impartiality and authority of open， fair， and just power dispatching. Based on an analysis of the problem with the existing evaluation indices of open， fair， and just power dispatching， a new index considering the coal price fluctuation for evaluating the openness， fairness， and justness of power dispatching is proposed. The index quantifies the difference in open， fair， and just power dispatching between generation enterprises， which can reflect the profit equity of generation enterprises. The examples indicate that the index proposed can be simply calculated and easily understood， contributing to further improving the openness， fairness， and justness of power dispatching.