This paper presents a fuzzy optimization method based on the inclusion degrees of intuitionistic fuzzy sets to solve multi-criteria decision making problems under fuzzy environments. First, the inclusion degree of intuitionistic fuzzy sets is defined and a series of specific formulas of inclusion degree are presented by means of the normal implication operators. Some formulas of inclusion degree of intuitionistic fuzzy sets are generalized by defining the cardinal number of intuitionistic fuzzy sets. Then, we give multi-criteria fuzzy decision-making method based on inclusion degree of intuitionistic fuzzy sets. Finally, we illustrate the effectiveness of the method proposed in this paper by an example.