In order to meet the requirements of complex index system and multiple evaluation subjects for reservoir safety evaluation, and to reduce the influence of the subjectivity and blindness of traditional variable weight AHP equilibrium coefficient on the objectivity and authenticity of the evaluation results, a variable weight AHP with improved equilibrium coefficient was proposed. Through the application to the Mamiao Reservoir project, the variable weight of secondary indicators and the fuzzy comprehensive score of primary indicators and overall objectives calculated by traditional variable weight AHP and improved variable weight AHP were compared and analyzed. The results show that the improved variable weight AHP can avoid the problem of state imbalance caused by the independent assignment of the equilibrium coefficient of each secondary index by the traditional variable weight AHP, and the blindness caused by giving the same equilibrium coefficient to each secondary index is appropriately weakened. The fit between the evaluation result and the current situation of reservoir safety is improved. The evaluation results are consistent with the conclusions of the expert group, which shows the reliability of the method in this paper.