Antioxidants are known to be beneficial to human health as they may protect the body against damage by reactive oxygen species,which can attack DNA,protein and membrane lipids and play a critical role in a variety of disease such as cancer,diabetes,cardiovascular disease and Alzheimer’s disease.However,there is much evidence that the use of natural antioxidants in foodstuffs is more attractive because of the potential health hazards associated with synthetic antioxidants in vivo.Turtle not only has a high nutritional value,but also has a potential medicinal value.In order to better know turtle’s nutrition and healthy function,the functional properties of enzymatic hydrolysates from yellow-margined box turtle(Cistoclemmys flavomarginata)muscle were investigated in this research.An enzymatic treatment procedure was devised to make the preparation of antioxidant peptide.By using a L₉(3⁴)orthogonal array design,the optimum conditions for hydrolyzing yellow-margined box turtle muscle with Alcalase to obtain antioxidant peptides with the highest hydroxyl radical scavenging activity were as follows:pH 8.0,temperature 55 ℃,material to liquid ratio 1.5∶20 g/mL,enzyme-to-substrate ratio 3.0% and reaction time 3 h.Under the above conditions,the scavenging rate of hydroxyl radical was 82.08%.Subsequently,the antioxidant properties of yellow-margined box turtle hydrolysates were determined in vitro.The results showed that the enzymatic hydrolysates had good scavenging abilities on hydroxyl radical(·OH),superoxide anion radical(O^2-·),α,α-diphenyl-β-picrylhydrazyl radical(DPPH·)and hydrogen peroxide(H₂O₂),and they also had certain reducing power,ferrous ion chelating capacity and the inhibition of linoleic acid autoxidation.In general,the yellow margined box turtle hydrolysates showed certain antioxidant activities in different systems in vitro,and they will have new and broad prospects.