Abstract: In order to optimize the key processing parameters for extracting crude polysaccharide from Hericium erinaceus by the fermentation of compound probiotics, this paper aimed to improve the extraction rate of crude polysaccharides and clarify their antioxidant activity. By using the single factor and orthogonal experiment methods, the effects of strain ratio, addition amount, temperature, time and initial pH value on the extraction rate of crude polysaccharide from Hericium erinaceus during the fermentation of compound probiotics were discussed, and the antioxidant activity of crude polysaccharide from Hericium erinaceus after the fermentation of compound probiotics was analyzed. The results showed that: compared with the fermentation without probiotics, the extraction rate of crude polysaccharide after the fermentation with compound probiotics (Lactobacillus plantarum∶Bacillus subtilis∶Streptococcus thermophilus was at a ratio of 1∶2∶1) was the highest (16.11%). Through the optimization of single factor and orthogonal experiments, the extraction rate of crude polysaccharide from Hericium erinaceus could reach 18.51% under the conditions of compound probiotic addition amount of 25%, fermentation temperature of 34℃, fermentation time of 12 h, and initial pH of 6.5. When the concentration of crude polysaccharide from Hericium erinaceus was 3.0 mg·mL⁻¹, the scavenging rates for DPPH, hydroxyl and ABTS free radicals were 71.26%, 86.90% and 84.59%, respectively.