The　basic　principle　of　an　optical　fiber　sensing　current　transformer　with　a　little　power　consumption　supplied　with　solar　cell　is　presented.　The　solar　cell　is　used　as　the　power　of　the　detecting　part　of　the　current　transformer,　thus　the　optical　fiber　sensing　system　can　be　operated　without　power　supply.　If　the　current　transformer　is　applied　to　on-line　monitoring　of　the　current　of　the　high　voltage　system,　not　only　the　higher　testing　accuracy　can　be　assured,　but　also　it　has　the　advantages　such　as　reliable　operation,　easy　adjustment,　low　cost　and　convenient　assembling.　The　system　has　good　adaptability.　The　real　time　on-line　monitoring　for　other　parameters　can　be　carried　out　if　its　sensors　are　changed.　It　opens　a　new　way　to　popularize　the　application　of　the　optical　fiber　sensing　system.