Abstract: The study investigated the polysaccharide extraction process and its antioxidant activity in vitro from passion fruit peel. Ultrasonic extraction method was applied,taking the polysaccharide yield rate as response value,based on single-factor test,optimized the conditions of the liquid-solid ratio,ultrasound power,ultrasound time and ultrasound temperature,and obtained the optimized parameters:the liquid-solid ratio was 49:1 (mL/g),ultrasound temperature was 69℃,ultrasound time was 15 min,and the ultrasound power was 150 W. Under these conditions,the average extraction rate of polysaccharide was 5.890%,closed to the predicted value of 6.09%. The results of antioxidant activity in vitro indicated that the polysaccharide had certainly scavenging ability to DPPH and hydroxyl radicals,which rates were 32.8% and 59.0%,respectively at 2 mg/mL,and also had the reducing ability,the absorbance value was 0.34,but weaker than vitamin C. The findings may provide a theoretical foundation for further research of its structure and new related products development of polysaccharide from passion fruit peel.