The evaluation of power market efficiency is related to the problems in the field of economy and electric power. The evaluation should take into account the market operation process, market operation effect and power grid structure. Combined with the power market efficiency evaluation method and the application of big data in the power industry, this paper analyzes the factors influencing the power market efficiency from the perspective of market and power grid structure, and constructs a three-level evaluation index system with the target of power market efficiency. The evaluation model is constructed by the weighted Mahalanobis distance based on the entropy weight method, and it is effective to evaluate the power market efficiency of a certain region by using the model. Based on the evaluation results, some suggestions are put forward for the standardized design of electricity transaction.