The　antioxidant　activity　of　collagen　have　not　been　reported　clearly,　however　the　antioxidant　activity　of　its　hydrolysate　collagen　peptides　have　been　reported　frequently.　In　order　to　study　the　essential　reason　causing　the　difference,　the　antioxidant　activity　of　collagen　mimetic　peptides,　collagen　peptides　mixture,　and　its　composing　amino　acid　(Proline,　Hydroxyproline　and　Glycine)　was　measured　by　T-AOC,　hydroxylamine　hydrochloride,　DPPH　and　ABTS　free　radical　methods;　and　the　secondary　structure　of　CMP　and　CP　determined　by　circular　dichroism.　It　was　found　that:　1)　The　CMP,　CP　and　various　amino　acid　didn＇t　exhibit　antioxidant　activity　in　the　T-AOC　method;　2)　Only　CP　showed　detectable　antioxidant　activity　in　hydroxylamine　hydrochloride　method;　3)　CP,　CMP　and　amino　acids　all　had　substantial　antioxidant　activity　in　DPPH　and　ABTS　methods,　with　an　order　of　CP＞Hypro＞CMP≥　Pro＞Gly;　4)　Circular　dichroism　data　showed　that　CMP　had　high　content　of　α-helix,　which　is　necessary　for　the　stable　triple　helix　structure　of　collagen;　however　CP　hadn＇t　apparently　α-helix　structure.　These　results　suggest　that:　1)　The　stable　triple　helix　structure　of　collagen　may　lead　to　its　antioxidant　activity　inconspicuously,　and　the　antioxidant　activity　of　collagen　peptide　relies　on　the　connection　of　amino　acid　residues　by　peptide　bonds　and　reachability　of　the　side-chain　of　amino　acid　to　free　radical;　2)　The　sensitivity　of　different　antioxidant　measurement　for　collagen　peptide　related　molecules　is　variable,　in　which　DPPH　and　ABTS　method　is　relatively　higher.　©　2017,　Editorial　Office　of　Journal　of　CIFST.　All　right　reserved.