Objective: This study aimed to improve the technological conditions of antioxidant activity of pumpkin polysaccharide. Methods:The effects of temperature, pumpkin powder/distilled water ratio of solid to liquid, inoculation amount and shaking speed on the extraction rate of bio-transformed pumpkin polysaccharide were investigated, and the scavenging ability of pumpkin polysaccharide on DPPH free radical was studied. Results:The optimal conditions were inoculation amount 1% and solid-liquid ratio 1∶30 (g/mL), with shaking speed of 100 r/min at 37 ℃. Under the control of these conditions, the scavenging rate of DPPH free radical was (54.61±1.58)%. The in vitro antioxidant activity of the bio-transformed pumpkin polysaccharide was significantly higher than that of the non-transformed one. Conclusion: Lactobacillus plantarum nbkBC299 could improve the antioxidant activity of pumpkin polysaccharide.