A soluble glucoside 3-dehydrogenase (G3DH) was purified from a newly isolated Sphingobacterium faecium ZJF-D6 CCTCC M 2013251. The enzyme was purified to 35.71-fold with a yield of 41.91 % and was estimated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis with a molecular mass of 62 kDa. The sequences of two peptides of the enzyme were all contained in a GMC family oxidoreductase (EFK55866) by mass spectrometry analysis. The optimal pH of the enzyme was around 6.2. The enzyme was stable within a pH range of 5.0-6.6 and was sensitive to heat. G3DH from S. faecium exhibited extremely broad substrate specificity and well regioselectivity to validoxylamine A. The enzyme was completely inhibited by Hg2Cl2 and partly inhibited by Cu2+, Fe2+, Ca2+, and Cd2+. The apparent K (m) values for D-glucose, sucrose, and validoxylamine were calculated to be 1.1, 1.7, and 2.1 mM, respectively. With this purified enzyme, 3-keto sucrose was prepared at pH 5.0, 30 A degrees C for 10 h with a yield of 28.7 %.