Abstract: In order to study the effect of iron reduction process on the anaerobic fermentation of Thermosiphio ferrireducens JL129W03^T, which was isolated from the deep-sea hydrothermal sulfide in the Northwest Indian Ocean, the cell growth and metabolites of strain JL129W03 with/without β-FeOOH as electron acceptor were quantitatively analyzed by cell counting， liquid chromatography and gas chromatography. The main metabolic pathway of JL129W03 was also analyzed based on its genome and it is anaerobic glycolysis pathway as result. It produces pyruvate resulting in the final metabolites of ethanol, acetic acid, lactic acid, butyric acid and CO₂. We also found that H₂ is produced by Fe-Fe hydrogenase which obtains electrons from the oxidation process of reduced ferredoxin. The addition of β-FeOOH to the medium significantly promoted the cell growth (from 3.17×10⁷ cells/mL to 2.19×10⁸ cells/mL) and the utilization of carbohydrates (such as starch and cellulose; increased 100% and 34%, respectively). The production of ethanol was significantly promoted (increased 76%) with β-FeOOH as electron acceptor, while the production of butyric acid was inhibited (reduced 73%). This study was helpful for understanding the physiological metabolism of strain JL129W03 and its further application for hydrogen and ethanol production.