In this study, effects of ultrasound processing time, ultrasound power and solid liquid ratio of ultrasonic on pumpkin polysaccharide extraction were investigated. The optimum parameters of extracting pumpkin polysaccharides are obtained by orthogonal test. Antioxidant activity were evaluated by using various established invitro systems, including 1,1-diphenyl-2-picrylhydrazylthe(DPPH•), hydroxyl(•OH) and FRAP system. Results showed that the extraction rate of polysaccharides pumpkin could up to 12.37% which the condition were water as extractant, ultrasonic time is 10min, ultrasonic power is 400w, solid to liquid ratio is 1:20. The polysaccharide raised the total antioxidant capacity in a dose-dependent manner. The results suggested that polysaccharide had direct and potent antioxidant activities.