The 3E system composed of “energy-environment-economy” is a key index to measure the coordinated development of cities.On the basis of summarizing and analyzing the traditional 3E system, the energy system is refined to coal system, and a set of evaluation index system with coal system, environment system and economic system as evaluation sub-targets is put forward.In this evaluation system, the subjective and objective weights are combined by game theory, which reduces the subjectivity of experts in scoring indicators.Based on the cloud model theory, an evaluation model of 3E system coordination degree is constructed.Taking the statistical data from 2014 to 2020 as an example, the evaluation model is used to evaluate the coordination level of 3E system in Inner Mongolia Autonomous Region.The evaluation results show that from the perspective of coordination degree of each subsystem, compared with the coordination degree of coal subsystem and environment subsystem, the economic subsystem lags behind, and the overall coordination degree of 3E system in Inner Mongolia Autonomous Region from 2014 to 2020 is in a good coordination level.The evaluation results are verifying the correctness and practicability of the evaluation model, and also providing reasonable opinions and suggestions for promoting the coordinated development of 3E system, and providing effective scientific basis for establishing and improving relevant policies.