Abstract: (-)-Epigallocatechin-3-gallate(EGCG) was loaded in chitosan nanoparticles for the preservation of antioxidant activity. The effects of the weight ratio of CS to PAA,p H,the reaction time and the concentration of Na Cl on the properties of EGCG-CS-PAA complexes were studied. All four factors significantly influenced the particle size,the Zeta potential,and the entrapment efficiency of EGCG. A stable and clear solution system could be obtained at p H3.5. The best EGCG-CS-PAA nanoparticles was obtained with the reaction time at 1hour and the weight ratio of 1∶1(CS∶PAA).Sustained free radical(ABTS+·) scavenging assays showed that the antioxidant activity of EGCG was retained by the nanoparticles. Meanwhile,EGCG nanoparticles were found to be a better protection of EGCG at high temperature and alkaline.