Abstract: The change of scavenging activity on DPPH· of the hydrolysates from Silybum marianum meal protein and on free radical scavenging activity of DPPH was selected as the index to investigate the effects of temperature,pH,food materials,preservative,metal ions and digestion mode on the antioxidation stability of the hydrolysates.The results showed that the activity retention rate of the hydrolysates was 92.19 % at 60 ℃ for 1 h. In the solution containing pH 3 or 11 for 2 h,its activity retention rate was 95.66 % and 86.69 %, respectively. In the solution containing NaCl,sucrose or glucose, its activity retention rate was all more than 96 %. In the 0.1 % solution of benzoic acid or sorbic acid , its activity retention rate decreased by 57.71 % and 45.48 %.These showed the hydrolysates has a strong heat-resistant ability. It can keep high activity in the acidity and alkali environment. NaCl,sucrose and glucose have little effects on its antioxidation stability while benzoic acid and sorbic acid can reduce its activity. All of K+, Ca2+, Mg2+, Fe3+, Zn2+, Cu2+ can affect the stability.In the 500 g/L solution of K+、Ca2+、Mg2+, its activity retention rare was all more than 90 %.In the 500 g/L solution of Fe3+, its activity retention rate was the lowest only at 48.64 %. And the hydrolysates can keep high activity in vitro digestive system.