Abstract: The Chihu hydrothermal field is the first detachment fault-type hydrothermal field discovered in the southern Mid-Atlantic Ridge by Chinese scientists. The structural characteristics of the Chihu hydrothermal field are different from those of previously discovered detachment fault-type hydrothermal fields. This hydrothermal field is located on the hanging wall of a detachment fault, and two hydrothermal vents have been discovered with the surrounding rock type of basic basalt. This study conducted mineralogical and geochemical analyses of sulfides from the Chihu hydrothermal field by using these methods of ICP-OES, ICP-MS, and LA-ICP-MS. The results showed that the sulfides in the study area can be sub-divided into the following three types: massive, brecciated, and disseminated sulfides. The sulfides in the Chihu hydrothermal field have distinct geochmical differences compared to other detachment fault-type hydrothermal sulfides. The main trace element compositions of bulk rock, trace element contents of pyrite, and sulfur isotope characteristics of sulfides in the hydrothermal field all indicate that the Chihu hydrothermal field may have been influenced by both of basic and ultrabasic rocks. The differences between the two hydrothermal vents in the hydrothermal field indicate that sulfide output from the same hydrothermal system at different periods underwent different later modifications.