Abstract: (R)-Tetrahydrothiophene-3-ol, a key intermediate of sulopenem (a novel 2-sulfanyl pennan compound, used for therapy of livestock bacterial diseases), has been highly desired for pharmaceutical use over the last three decades. Apart from the complicated and environmentally unfriendly chemical synthesis, the most straightforward approach for this synthesis is the biological asymmetric reduction of tetrahydrothiophene-3-one. A high enantioselective ketoreductase is needed to accomplish this reaction. However, it is difficult to screen a high enantioselective ketoreductase towards the nearly spatially symmetrical substrate, tetrahydrothiophene-3-one. Some researches have been conducted to work on this issue, where mere enantiomeric excess (e.e.) or long reaction time was observed. In this study, a new enzyme (designated as BaCR1) from Bacillus anthracis str. Ames by library screening has been explored, which can be used for asymmetric synthesis of (R)-tetrahydrothiophene-3-ol. The characteristics of this enzyme were further investigated after protein purification by affinity adsorption separation with Ni-column. After performing reaction optimization, we found that the optimal pH value and temperature of BaCR1 for catalysis reaction was 7.0 and 30℃, respectively. k_cat/K_M was 0.25 L/(mmol·s), using a substrate concentration ranging from 0.125 mmol/L to 50 mmol/L. The half-life of purified BaCR1 was 9.63 h and 3.04 h at 30℃ and 40℃, respectively, suggesting good thermostability of BaCR1 in the catalysis reaction system. Finally, (R)-tetrahydrothiophene-3-ol was prepared in 100 mL scale. Without extra addition of NADPH, the reaction conversion could reach 99% with 84% of e.e. at the substrate loading of 50 mmol/L. Considering that this is a nature parent enzyme, the result is reasonably acceptable, which also reveals the potential of enzyme-catalyzed asymmetric synthesis of (R)-tetrahydrothiophen-3-ol.