Abstract: In order to improve the extraction rate of Submerged Mycelium Polysaccharide from Pleurotus nebrodensis, the influences of enzyme dosage , enzymolysis temperature, enzymolysis time and pH value on its yield were studied. A quadric regression model was established. The model fitted significantly well and the optimum combination was obtained. The responses of the polysaccharides yield to all four single factors and their double factors interaction were discussed. Results show that when the extraction parameters are controlled at enzyme dosage 2.53%, enzymolysis temperature 39.6℃, enzymolysis time 3.2 h and pH value 7.2, the polysaccharides yield could be up to 8.23%.