Biotransformation of antimony (Sb) is a newly discovered process regulating the Sb redox transformation in soils. Understanding such biogeochemical process may contribute to future bioremediation strategy to remove Sb from environments. In comparison to As, the relative of Sb belonging to the same group of periodic table, the biotransformation of Sb is much less studies. Our current understanding of the Sb-oxidizing and –reducing bacteria is entirely based on several pure isolates. In this study, we employed the stable isotope probing coupled with the metagenomic-binning to identify the microorganisms participating the Sb oxidation and reduction and reveal their potential mechanism to transform Sb. Sb-contaminated soils sampled from active Sb mining area were selected. Metagenomic analysis on this soil indicated that As-related genes (e.g., arsC and aioA) are correlated with Sb species, suggesting that microorganisms may use similar pathways to oxidize or reduce Sb as As. In order to verify this observation, DNA-SIP was performed to identify the potential Sb oxidizers and reducers in the microcosms inoculated from Sb-contaminated rice paddy soils and dry land soils. DNA-SIP indicated that Pseudomonas, Lysinibacillus, and Geobacter may be the potential Sb(V)-reducing bacteria. Further, metagenomic-binning was performed to reveal the physiological traits of the potential Sb(V)-reducing bacteria identified by DNA-SIP. Our data indicated that the Sb(V)-reducing bacteria may use the respiratory arsenate reductase (arrABD) to reduce Sb(V) to Sb(III). However, members of Lysinibacillus may use other mechanisms to transform Sb(V) instead of arrABD. Sb(III) oxidation also represents a very important geochemical process, which can reduce the toxicity of Sb. Therefore, experiments are currently on the way to identify the potential autotrophic Sb(III)-oxidizing bacteria in microcosms seeded from Sb-contaminated soils. Several novel Sb-metabolizing bacteria were identified in this study, indicating that DNA-SIP is a powerful tool to identify the Sb-metabolizing bacteria. The combination of DNA-SIP and metagenomic-binning suggested the effectiveness of these advance molecular techniques in unravelling the mystery of biotransformation of Sb. This work represents the first application of DNA-SIP and metagenomic-binning to identify Sb-metabolizing bacteria and their potential metabolic potentials and therefore provides a valuable set of data to definitively link identity with Sb cycling. The identification of novel putative Sb-metabolizing bacteria expands current knowledge regarding the Sb cycling.