Abstract: In thermodynamics，there are two different assertations about the set of variables for the chemical po-tentials of manysubstances． One is that the chemical potential of a certain substance only depends on the existence of other substances; and another is that it depends not only on other substances，but also onitself． Through a detailed a-nalysis，it is demonstrated the chemical potential in general depends on all substances within thesystem．

Key words: Thermodynamics, chemical potential, characteristic function, intensity quantity, extensive quantity