Abstract: To study the antiseptic and antimicrobial effect of natural biopreservative ε-polylysine,oysters stored at(4±1) ℃ were treated with two concentrations of ε-polylysine(0.2% and 2%). By monitoring the total bacterial counts,pH,total volatile base nitrogen(TVB-N),texture profile analysis,and free amino acids compositions during storage,the quality of oysters were evaluated. ε-polylysine showed potential antiseptic and antimicrobial effects on oysters in this study. Compared with blank group,2% ε-polylysine could significantly reduce the number of colonies by at least one order of magnitude at the first 5 days of the preservation process,as while as the value of the TVB-N decreased by 3.59 mg/100 g(P<0.01). Otherwise,the obvious differences appeared at three indicators,containing pH,TPA and FAA from the 10th to 13th day because of 2% ε-polylysine(P<0.05),especially at hardness with extremly significant increasing(P<0.01). Moreover,the contents of Glu and Gly changed gently after the 10th day in the 2% ε-polylysine group,which was significantly different from the blank group(P<0.05).At the 19th day,the FAA was lower than that of the blank group for 16.98 mg/g(P<0.01). The results showed that ε-polylysine could inhibit the proliferation of microbes and delay the oyster decay,which indicated ε-polylysine had potential application for the development of biopreservatives for the aquatic products.