In this study, response surface methodology (RSM), based on Box-Behnken design, was employed to optimize the extraction conditions of polysaccharide from Clematis huchouensis Tamura (CP). And then the antioxidant activities of the samples were investigated including scavenging effects of superoxide and hydroxyl radicals and their reducing power. The results of chemical composition and FT-IR spectrum analysis showed the polysaccharide was acidic proteoglycan. And moreover, CP showed excellent antioxidant activity in these three assays. The purification and structure of CP need to be further studied.