A novel b-mannanase-producing strain, Bacillus subtilis TJ-102, was identified and characterized. Response surface method was applied to improving and enhancing the enzyme production. The optimized media components were obtained: 45.25 g/L konjac, 9.29 g/L Na2HPO412H2O, 2.60 g/L CaCO3, 1.0 g/L (NH4)2SO4, 0.3 g/L KH2PO4, 1.0 g/L NaCl, 1.0 g/L MgCl26H2O, and 0.01 g/L FeSO4. Under these conditions, the b-mannanase activity could achieve 205.3 U/mL in a 7-L fermentor. Then, b-mannanase was 7.39-fold purified by salting out, ultrafiltration, anionexchange, and size-exclusion preparative chromatography with a recovery of 21.41 % and a specificity of 125.36 U/mg proteins. b-Mannanase was stable below 65 C and pH 5.0–8.0, which exhibited excellently enzymatic efficiency in the preparation of gluco-mannooligosaccharides (GMOS) by hydrolyzing konjac flour. The GMOS yield of 57.76 % has been achieved with 8.71 % of mannose and 14.49 % of glucose, demonstrating the potential use of b-mannanase in food industry.