The extraction process of Citrus reticulate peel polysaccharide was studied by single factor experiment which controlled extraction temperature, extraction time, ultrasonic power and liquid ratio. The orthogonal experiment was texted and based on single factor experiments, then determined the best extraction process by experimental data. The oxidation resistance of Citrus reticulate peel polysaccharide was determined by Fenton reaction. The results showed that the extraction rate of Citrus reticulate peel polysaccharide could reach 28.86% when the extraction temperature was 70 ℃, extraction time 50 min, ultrasonic power 280 W, solid-liquid ratio 1∶25(g/mL). The hydroxyl radicals were cleared by Citrus reticulate peel polysaccharide which showed Citrus reticulate peel polysaccharide had oxidation resistance, then Polysaccharides and hydroxyl free radical clearance existed concentration-response relationship.