The chemical constituents and antioxidant potentials of Hipopphae rhamnoides L. leaves and its black tea product were investigated. Methods: The contents of tea polyphenols, flavonoids, polysaccharides and caffeine were analyzed by Folin colorimetric method, Sodium nitrite-aluminum nitrate-sodium hydroxide colorimetric method, Phenol-sulfuric acid method and national standard method of "Theophylline determination"; Four methods including DPPH?, ABTS+, ?OH and reducing power were used to evaluated antioxidant activity. Results: The main chemical components of the black tea: tea polyphenols was 18.45%, flavonoids content was 2.51%, polysaccharides content was 15.56% and caffeine content was 3.06%; the results of in vitro antioxidant experiments showed that the IC₅₀ of Hipopphae rhamnoides L. leaves and its  black tea on scavenging DPPH?, ABTS+ and?OH free radicals were 2.47 mg/mL and 0.76 mg/mL, 0.0040 mg/mL and 0.0038 mg/mL, 0.48 mg/mL and 0.41 mg/mL, respectively. They also had a certain reducing power and a good concentration dependence. Conclusions: The antioxidant activity of black tea is better because of  active ingredients such as tea polyphenols, flavonoids and polysaccharides.