Abstract: In this paper, konjac powde were hydrolyzed by Bacillus licheniformis to prepare oligosaccharides. The effects of concentration of konjac powder, inoculum amount of strain, bacteriolysis temperature and hydrolysis time on hydrolysis rate of konjac powder were determined by single factor tests. The antioxidant activity of konjac powder oligosaccharides was evaluated with the scavenging ability of ·OH, ·O₂⁻· and DPPH· as indexes. The prebiotic activity of konjac powder oligosaccharides was investigated by in vitro fermentation test. The results showed that the optimal hydrolysis process parameters was as follows: concentration of konjac powder 20 g/L, inoculation capacity 1×10⁷ CFU/g, hydrolysis temperature 43.6 ℃, hydrolysis time 10.2 h. Under the optimal conditions, the hydrolysis rate of konjac powder was 39.06%±0.12%, and the yield of KGOS was 66.72%. With the prolongation of hydrolysis time, the viscosity of solution decreased from 2430.33 mPa·s to 18.06 mPa·s. When the concentration of konjac powder was 10 mg/mL, the clearance rates of ·OH, ·O₂⁻ and DPPH· were 61.47%, 34.60% and 81.43%, respectively. The OD₆₀₀ of KGOS, glucose and konjac powder on the proliferation of Lactobacillus plantarum, Lactobacillus brevity and Lactobacillus casei in vitro were 0.775, 1.371, 0.236, 0.791, 1.339, 0.224 and 0.916, 1.336, 0.243, respectively. The results provide a theoretical basis for the further processing and utilization of oligosaccharides in konjac powder.