The　membrane-separated　silver　carp　hydrolysates　(＞10　kD,　3-10　kD　and　＜　3　kD)　displayed　abilities　to　mitigate　oxidation　and　denaturation　of　myofibrillar　protein　and　cryoprotective　activities　for　frozen　surimi.　However,　the　mechanism　of　the　membrane-separated　fractions　on　ice　crystal　growth　in　the　system　is　still　unknown.　Therefore,　the　cryoprotective　activities　(recrystallization　inhibition,　RI　and　thermal　hysteresis　activity,　THA)　of　the　fractions　were　investigated　and　the　mechanism　was　explored　by　molecular　dynamics　(MD)　simulation　to　predict　the　probable　binding　sites　and　model　the　possible　interactions　between　the　peptides　and　water/ice.　The　fractions　＜　3　kD　displayed　remarkable　RI　activity,　with　significantly　higher　THA　(0.60　+/-　0.13　degrees　C)　and　lower　amount　of　ice　nuclei　(4.74　+/-　0.53%)　than　that　of　fractions　＞　10　kD　and　3-10　kD.　The　results　of　MD　simulation　certified　that　the　main　peptides　in　the　fractions　＜　3　kD　interacted　firmly　with　water　molecules　and　inhibited　growth　of　ice　crystals　with　mechanism　compatible　with　Kelvin　effect.　Hydrophilic　and　hydrophobic　amino　acid　residues　in　the　membrane-separated　fractions　offered　synergistic　effects　on　the　inhibition　of　ice　crystals.