In　the　present　study,　polyphenols　from　Porphyra　haitanensis　(PP)　were　extracted　and　separated,　and　their　in　vitro　antioxidant　activity　was　investigated　by　1,　1-diphenyl-2-picrylhydrazyl　(DPPH)　radical　scavenging　capacity,　the　ability　to　inhibit　the　color　fading　of　β-carotene　and　ferric　reducing　antioxidant　power　(FRAP),　as　well　as　their　protective　effect　against　oxidative　damage　induced　by　ultraviolet　radiation　B　(UVB)　in　human　skin　fibroblast　cells　(HSFs).　The　aim　of　this　investigation　was　to　ascertain　the　applicability　of　PP　to　protect　the　skin　against　UV　damage.　In　vitro　tests　demonstrated　that　PP　had　strong　antioxidant　activity,　whose　DPPH　radical　scavenging　capacity　was　equivalent　to　that　of　BHT　at　the　same　concentration　but　whose　ability　to　inhibit　the　color　fading　of　β-carotene　in　the　presence　of　linoleic　acid　and　FRAP　were　weaker.　The　cellular　experiment　showed　that　PP　significantly　reduced　lactic　dehydrogenase　(LDH)　leakage　from　HSFs　induced　by　UVB　irradiation,　maintained　cell　membrane　integrity,　decreased　reactive　oxygen　species　(ROS)　level,　enhanced　the　activity　of　antioxidant　enzymes　such　as　superoxide　dismutase　(SOD)　and　glutathione　peroxidase　(GPx),　therefore　attenuating　cellular　oxidative　stress,　enhancing　the　oxidative　stress　resistance　of　endothelial　cells　and　significantly　inhibiting　the　apoptosis　of　HSFs.　These　findings　led　us　to　conclude　that　PP　can　protect　HSFs　against　UVB-induced　oxidative　damage　and　has　potential　for　protection　against　UV-induced　skin　damage.　©　2017,　China　Food　Publishing　Company.　All　right　reserved.