A novel optical fiber sensor based on location surface plasma resonanc e (LSPR) for cardiac troponin I (cTn I) detection is proposed.A standard optical fiber is used and its extr amural cladding is partially corrupted by hydrofluoric acid.Nanometer silver membranes are formed on the su rface of the corrupted fiber.A staphylococcal protein Ais used as the ligation mediator between the nanometer silver membranes and cTn Imonoclonal antibodies.The optical fiber sensor is modified with mouse anti-hu man cTn Imonoclonal antibody. It is put into cTn Isolution with different concentrations.The cTn Iconcentra tion can be obtained by measuring the extinction peak shift of spectrum curves.The experimental results show that there is a linear relationship between the logarithm of extinction peak shift and the logarithm of mass concentration o f cTn Iin the range of 20－120ng/mL with a linear dependent coefficient of 0.9962.U t ilizing the sandwich method,the detection limitation of the optical fiber sensor can achieve 10ng/mL with a strong abilit y of anti-jamming to other proteins. The optical fiber sensor based on LSPR proposed here is compact,robust,cost effe ctive,highly sensitive,and suitable for cTn Idetection.