Abstract: Large-scale infrastructures have comprehensive impacts on society, economy, environment and so on. In the uncertain environment, the traditional project economic evaluation tends to be influenced by the preference, experience and other factors of the evaluator. Furthermore, in the process of evaluation, many indexes can't be compared and measured exactly, and may be fuzzy. And hence, based on the interval number theory and cluster analysis method, this article sets up the project economic evaluation group decision-making model. Lastly, the model is put into application.