Abstract: ObjectiveThe present experiment was conducted to optimize the extraction process of polysaccharide from Ostrea rivularis Gould, in order to provide a theoretical basis for comparing and analyzing content and structure of oyster polysaccharide in different sea areas. MethodThe effects of liquid-solid ratio, extraction temperature, extraction time and extraction times on extraction rate of polysaccharides from O. rivularis were investigated by single-factor test. Mean-while, based on the results of single-factor test, liquid-solid ratio, extraction time and extraction temperature was chosen as independent variables, and the extraction rate of oyster polysaccharide was selected as response value. Then the regres-sion model was established by Box-Behnken experiment design method, so as to optimize extraction process of polysaccha-ride from O. rivularis. ResultThe mathematical model for quadratic polynomial of polysaccharide extraction rate (Y) with liquid-solid ratio(A), extraction time(B), extraction temperature(C) was established by response surface method, as fol-low:Y=9.65-0.18A-0.071B+0.080C-0.27AB-0.24AC-0.52BC-2.6A2-1.34B2-1.35C2, with high fitting degree. The opti-mum conditions of extraction process were as follows:90∶1 of liquid-solid ratio, 90℃of extraction temperature, 3 h of ex-traction time, extracting 1 time. Under the above optimum conditions, the extraction rate of polysaccharide from O. rivularis reached up to 9.72%, which was close to the predicted value(9.66%), with relative deviation of 0.62%. ConclusionThe response surface methodology is a workable method to optimize extraction conditions of polysaccharide from O. rivularis, which should be applied to increase effectively extraction rate of polysaccharides in actual production.