Crude catechins extracted from green tea had an ability of eliminating free radicals of active oxygen. The antioxidative activity of the catechins was 3.93 times higher than that of ascorbic acid. By adding 0.05% of the catechins to lard, the auto-oxidation induction phase of the lard was prolonged for 12 times, the peroxide value and the propanedialdehyde concentration were statistically lower at the level of P=0.01. In a model system of simulated stomach condition, the crude extract eliminated NaNO2 and inhibited the formation of N-nitroso compound's obviously, the elimination rate and the inhibition rate were 96.9% and 98.6%, respectively.Experiment in fowls showed that the extract could decrease the plasma total cholesterol and triglyceride