The purpose of this study was to investigate the chemical composition of the freeze-dried stems and fruit of the cactus Cheonnyuncho. The analysis showed that powdered stems have the highest fat content (1.91%) and the powdered fruits have he highest protein content (2.62%). The K content of the fruits higher than that of the stems, while the Ca, Mg, Na and P contents of the stems were higher than those of the fruits. Both the stems and fruits powders contained high levels of the amino acids glutamic acid and aspartic acid. The free sugars such as sucrose, fructose, and glucose were detected in both the stems and fruits. The 75% ethanol (EtOH) extract showed a relatively high antioxidative activity compared to those of the water and 75% methanol (MeOH) extracts. Furthermore, the 75% EtOH extract of the stem powder exhibited a total polyphenol content of 3.60 g/100 g, and a total flavonoid content of 2.00 g/100 g. The antioxidant activities of the stem and fruit powder extracts, measured in DPPH radical scavenging experiments, were higher than that of the control group.