S-Ribosylhomocysteinase(LuxS) is the key enzyme in the synthetic pathway of a quorum sensing autoinducer AI-2. LuxS from a 2,3-butanediol produced strain Klebisella pneumoniae CICC 10011 was cloned and characterized. The luxS gene is composed of 540 bp with 172 amino acids encoded. The Km value for S-ribosylhomo- cysteine(SRH) was (27±1) umol/L, kcat was (0.112±0.004) s-1 and kcat/Km was 4.4×103 L umol-1·s-1 at 25 ℃. LuxS was activated by divalent metal ions, the highest activity was detected with Co2+ form, followed by Mg2+, Ba2+, Mn2+, Fe2+ and Ca2+, and activation constant for Co2+ is (16±2) umol/L. The LuxS from the 2,3-butanediol produced strain Klebisella pneumoniae CICC 10011 was cloned and characterized. The luxS gene is composed of 540 bp The Km value for S-ribosylhomo-cysteine ​​(SRH) was (27 ± 1) umol / L, kcat was (0.112 ± 0.004) s-1 and kcat / Km was 4.4 × 103 L umol-1 The highest activity was detected with Co2 + form, followed by Mg2 +, Ba2 +, Mn2 + L.