As an important part of energy transformation, integrated energy system (IES) has attracted widespread attention from more and more countries. Establishing an evaluation system and method for IES that matches China's national conditions can not only lay a foundation for post-evaluation of IES planning and rank the planning schemes accordingly, but also improve the management level of IES projects and provide a reference for formulating a unified and complete IES evaluation criterion. To this end, combining the basic characteristics and operational features of the park IES, a comprehensive evaluation index system including four aspects of economy, reliability, environmental protection, and intelligence and friendliness is constructed. Then, to address the uncertainty of IES operation, the comprehensive evaluation system based on the traditional cloud matter-element model proposes cloud entropy optimization, considering the varying degrees of acceptability of fuzziness among different evaluators. To solve the problem that the evaluation results caused by a single weighting method may be too subjective or too objective, a comprehensive weighting method combining the decision making trial and evaluation laboratory method with the entropy weight method based on the principle of minimum discrimination information is selected, and the variable weight method is used to further improve the value of comprehensive evaluation index. Finally, the scientific correctness of the proposed comprehensive evaluation system is verified through case analysis.