Abstract: Objective:This study was aimed to optimize polysaccharides extraction from Urena lobata L. by cellulase enzymolysis approach and investigate its antioxidant activity. Methods:The mathematical model was established by response surface method(RSM)based on the results of single factor experiments,using polysaccharides extraction rate as response value and the ratio of water to material,cellulase concentration,extraction temperature and time as experimental factors,which was used to screen optimum polysaccharide extraction conditions from Urena lobata L.. Antioxidant activity of polysaccharides was studied by DPPH and ·OH free radical elimination method.Results:The optimum conditions obtained by RSM were as follows:The cellulase level was 10.8 mg/mL,extraction time duration was 72 min,the ratio of water to feedstock was 7:1 mL/g,extraction temperature was 43℃,the pH value was 5.0. Under the optimal conditions,there was a difference of less than 5% between predicted extraction rate 13.37% and experimental extraction rate 13.32%. IC₅₀ of DPPH and ·OH were 1.082 mg/mL and 3.202 mg/mL,respectively. Antioxidant activity of sample polysaccharides was weaker than those of vitamin C. Conclusion:The polysaccharide extraction process from Urena lobata L. by cellulase enzymolysis approach was obtained,which was convenient and feasible,and extracted polysaccharides had good free radical scavenging activity.