In this paper, the group decision making problem is investigated, where all the information are measured by interval-valued intuitionistic fuzzy numbers(IVIFNs), and the decision-makers are presented as interval-valued intuitionistic fuzzy decision matrices. Meanwhile, by translating the interval-valued intuitionistic fuzzy number(IVIFN) into a fuzzy number(ZFN), a new ranking method on interval-valued intuitionistic fuzzy decision making is proposed. Practical example shows that the proposed approach is simpler and more convenient than existing methods.