A green building involves complex system engineering including energy efficiency and energy utilization, water-saving and water utilization, material-saving and material utilization, and land-saving and indoor environment quality and operation management. In order to solve problems of subjectivity, uncertainty and impossibility of quantitative analysis when evaluating green building, this study establishes a multi-level fuzzy evaluation model by means of fuzzy mathematics method to analyze the comprehensive performance of green building according to the index system of “Evaluation Standard for Green Building”. Combined with the technique scheme of the first China green building demonstration project, the result proves to be in accordance with the pre-evaluation of experts. It shows that the fuzzy comprehensive evaluation method is reasonable and feasible to evaluate the comprehensive performance of green building. The evaluation result is the same as the pre-evaluation result. Factors with high weights have larger effects on the results. This proves that the guideline should be the first reference mode in the future engineering practice so as to realize optimization of green building performance.