The energy consumption problem of building complexes has become increasingly prominent along with the acceleration of urbanization. In order to achieve efficient energy saving in building complexes, this study proposes a Bayesian network-based uncertainty modeling in decision-making system for energy consumption management. By analyzing the uncertainty factors in the energy consumption data, a Bayesian network model is constructed to predict and analyze the energy consumption. And the uncertainty factors are used as decision variables to construct the energy consumption management decision-making system based on Bayesian network. The experimental results show that the uncertainty model and decision-making system constructed in this paper have more favorable performance compared with other benchmark methods, and exhibit smaller measurement errors in experimental tests. At the same time, the application of this paper’s decision-making system for energy consumption management of building complexes can significantly reduce management costs, and obtain the double benefits of reducing energy consumption and saving costs.