In nature, copper mainly occurs in sulfide minerals. At present, only the sulfur β-factors of several Cu-bearing sulfides and the iron β-factor of chalcopyrite have been determined, and the β-factors determined by different researchers are different, impeding the application of S and Fe isotopes as powerful tracers in tracing the formation and evolution of porphyry copper deposits. In this study, the first-principles methods are used to compute the reduced partition function ratio of S isotopes (10³lnβ_34-32) for Cu-bearing sulfides as well as the reduced partition function ratio of Fe isotopes (10³lnβ_57-54) for Cu-Fe sulfides in the temperature range of 0~1 000℃. 10³lnβ_34-32 decreases in the order of covellite>cubanite>chalcopyrite ≈ villamaninite>bornite>chalcocite, and 10³lnβ_57-54 decreases in the order of cubanite ≈ chalcopyrite>low-bornite>high-bornite>intermediate-bornite>intermediate-Cu₈Fe₄S₈. 10³lnβ_34-32 of Cu-bearing sulfides displays weak correlations with S coordination number, the average metal-sulfur bond length, and the average bond lengths of all the bonds formed by S, while 10³lnβ_57-54 of Cu-Fe sulfides displays an approximately negative correlation with the average Fe-S bond length. S isotope fractionation caused by the phase transition of chalcocite is very large, while S isotope fractionation caused by the phase transition of bornite is negligible. The results of this study can provide theoretical evidence for tracing porphyry copper deposits and other types of sulfide deposits.