When　there　is　time　offset,　a　passive　position　estimation　method　is　put　forward　for　TOA-based　sinal　travel　model　from　transmitter　to　receivers　via　target.　By　transforming　the　positioning　model　to　linear　equations　which　can　be　directly　represented　as　algebraic　solutions　of　target　positions,　the　initial　solution　of　target　position　is　obtained　by　introducing　the　extra　variables.　Then　the　localization　refinement　is　put　forward　to　improve　the　performance.　The　simulations　are　conducted　to　test　the　impacts　of　noises　on　the　localization　accuracy.　The　results　show　that　the　performance　of　localization　refinement　can　approximately　attain　the　Cramr-Rao　lower　bound　of　target　position.　©,　2015,　Binary　Information　Press.　All　right　reserved.