A mathematical model is created, and the algorithm is designed according to the fuzzy clustering. The main indices of the soy sauce samples are detected, and the data are analyzed using fuzzy clustering. As a result, many classes including different soy sauce sample can be obtained, and the quality within the same class is similar. The mathematical model and algorithm provide a method to identification the soy sauce. And in the others, it provides a new method to evaluate the quality of the soy sauce.