On the basis of the global stability of mix-valued logical networks, the concept of set stability is preposed, which determines whether a given system converges to a given subset. This paper investigates the set stability of mix-valued logical networks. Firstly, the mix-valued logical networks are introduced, which are translated into discrete linear dynamic equations by using the semi-tensor product of matrices. Then, the concept of invariant subsets is introduced, and a method of searching for the largest invariant subset is proposed. Based on above, a necessary and sufficient condition for set stability of the concerned networks is developed. Finally, the stability of partial states is proposed, and is converted to the study of set stability for a certain subset. A numerical example is given to illustrate the effectiveness of the obtained results.