Polarimetric　fiber-optic　current-sensing　technology　is　typically　employed　for　measuring　high　current,　as　the　low　Verdet　constant　of　optical　fiber　makes　Faraday　rotation　not　noticeable　in　low-current　measurements　and　subsequently　leads　to　low　current　sensitivity.　To　enhance　current　sensitivity,　a　polarimetric　method　based　on　a　reflective　polarization-bias-added　(RPBA)　structure　is　presented　in　this　article.　First,　it　is　proved　by　the　Jones　matrix　that　current　sensitivity　would　be　compromised　due　to　the　constant　term　in　the　traditional　sensing　output.　Then,　the　single-axis　measurement　method　is　employed　to　eliminate　the　constant　term　using　the　single-axis　working　(SAW)　circulator.　In　consideration　of　the　accuracy　of　subsequent　signal　decoding,　the　bias　is　generated　by　the　RPBA　structure　to　process　optical　signals　between　the　circulator　and　the　mirror.　Next,　a　decoding　algorithm　based　on　parameter　optimization　is　presented　to　restore　the　measured　current　from　the　photodetector　output.　Finally,　the　experimental　results　show　that　the　current　sensitivity　of　the　presented　method　can　be　larger　than　0.005　V/A　under　the　premise　of　small　measurement　error　in　the　vibration-and-temperature　test.　Compared　with　the　existing　polarimetric　methods　whose　current　sensitivity　tends　to　be　0.002　V/A,　the　presented　method　has　better　current　sensitivity　without　incurring　additional　sensor-head　turns　or　optical　devices.