So far the DEMATEL decision making method based on uncertain linguistic information are more suitable for small and medium-sized group, and do not consider uncertain linguistic variables use the non-uniform evaluation scale. To overcome this kind of defects, a new large-scale group DEMATEL decision making method under uncertain linguistic information is proposed. Firstly, a reasonable cluster method for uncertain linguistic group DEMATEL matrix is given, which is used to make a cluster for large-scale group DEMATEL evaluation information. Secondly, the three dimensional uncertain linguistic density operator is defined, which is used to aggregate large-scale group DEMATEL evaluation information. Finally, a improved index weights calculation method based uncertain linguistic information is proposed, on this basis, the multiple attribute decision making is implement. One numeral example is used to illustrated the feasibility and effectiveness of the proposed method. The results show that the decision making is rational and credible as it can use the uncertain linguistic variables with non-uniform evaluation scale and consider large-scale group decision making’s consensus degree.