A　linear　optical　current　transducer　(OCT)　based　on　radial　polarization　demodulation　was　proposed.　A　magnetic　concentration　ring　with　an　air　gap　was　selected　as　the　sensing　head,　in　which　two　magnetizer　plates　were　used　to　lead　out　the　magnetic　field　of　air　gap,　and　the　straight　optical　path　passed　through　the　air　gap　by　light　apertures.　The　reflecting　prism　was　not　needed　so　that　the　reflection-induced　retardation　was　eliminated,　which　helped　to　improve　the　stability　of　the　transducer.　A　radially　polarized　grating　was　employed　to　convert　the　Faraday　rotation　angle　into　the　rotation　of　a　circular　facula,　which　was　detected　by　a　four-quadrant　detector,　and　then　the　measured　current　could　be　obtained　after　signal　processing.　The　theoretical　analysis　and　experimental　results　show　that　this　new　OCT　has　a　measurement　range　of　±43°　in　Faraday　rotation　angle　and　the　advantage　of　optical　power　independent,　meeting　the　national　standard　of　0.2S　accuracy　class.　©　2018,　Editorial　Board　of　Journal　of　Infrared　and　Laser　Engineering.　All　right　reserved.