Smilacis Chinae Radix is root of Smilax china L.. It has been known as a korean folk medicine for anti-inflammatory, anti-microbial diuresis, detoxification and relieving enteropathy as diarrhea. Reactive oxygen species(ROS) are continuously produced at a high rate as a by-product obtained in the aerobic metabolism. A major portion of living organisms has defense system as superoxide dismutase or catalase against damage produced by ROS. Several lines of evidence provided that ROS appears to cause to develop aging and various diseases. In this study, we have investigated the antioxidant activities of Smilacis Chinae Radix in order to screen the antioxidant substances from natural products. As a result, EtOAc extract of Smilacis Chinae Radix exhibited potent antioxidant effect on various antioxidant experiment. The major components of antioxidant activity were isolated from EtOAc extract of Smilacis Chinae Radix. Their structure of compounds were identified as quercetin and (-)-epicatechin by spectroscopic evidence, respectively.