Precipitation method was used to prepare hydroxylated iron oxide (α-FeOOH) adsorbent to test its adsorption capacity for H2S using a fixed bed gas chromatography platform in this work. It was found that its sulfur capacity reached 63.8 mg/g, and the effects of O2 and H2O atmospheres on sulfur capacity were tested. It was found that there were optimal concentrations for O2 and H2O under the selected conditions, being 0.3vol% and 3vol%, respectively. The physicochemical properties of adsorbents and the occurrence forms of sulfur-containing components were characterized by XRD, XPS, TG, and CO2-TPD. It was found that the main sulfur-containing species were elemental sulfur and sulfate (SO42-) after α-FeOOH adsorbed H2S. The role of O2 in the reaction was analyzed by pre-adsorbing oxygen test. The adsorbed oxygen promoted the formation of sulfur elemental, while the presence of gaseous O2 increased the proportion of SO42-. In situ diffuse reflectance infrared spectroscopy showed the intermediate products adsorbed by H2S. H2S combined with the lattice oxygen or hydroxyl groups on α-FeOOH surface to generate HS-, and then HS- was further oxidized by Fe3+ with electron transfer to generate elemental sulfur, or HS- was oxidized by O2 to generate SO42-. This work provides a theoretical basis for the optimization of adsorbent preparation and the application of blast furnace gas purification technology.