An iridium/iridium oxide electrode for quantitatively detecting pH in a sulfide ion environment, and a preparation method and use thereof are provided. In the present disclosure, a sensitive layer of the iridium/iridium oxide electrode is coated with a sulfonated polyether ether ketone/ionic liquid (SPEEK/IL) sandwich structure. The SPEEK/IL sandwich structure includes two layers of SPEEK/SiOx/IL composite film and one layer of SPEEK film. The SPEEK film is arranged on an outermost layer. The SPEEK/IL sandwich structure covered on a surface of the electrode has an isolation effect on ions other than hydrogen ions, and especially shows a desirable isolation effect on sulfide ions with a smaller ion size. In this way, the electrode is not easily disturbed by redox substances in a complex aqueous environment.