With　the　rapid　development　of　metal　halide　perovskite,　reducing　its　dimensionality　into　two-dimensional　(2D)　or　one-dimensional　(1D)　nanostructures　has　been　reported　to　be　a　good　alternative　for　expanding　the　spectral　absorption　or　emission　range.　For　example,　when　substituting　monovalent　cation　Cs+　with　phenyl-ethylammonium　(PEA(+))　on　fabricating　2D-CsPbI3,　the　photoluminescence　peak　processes　a　maximum　regulation　from　710　to　625　nm.　Simultaneously,　when　slicing　into　1D　CsPbI3　nanowires,　the　light　emission　could　also　achieve　a　maximum　blue　shift　from　700　to　600　nm.　Herein,　by　using　a　ligand-assistant　reprecipitation　(LARP)　method,　oleic　acid　(OA)　molecule　is　successfully　inserted　into　the　lattice　of　one-dimensional　CsPbI3　nanowire　(namely　OA-CsPbI3),　which　presents　a　monochromatic　yellow　light　emission　at　558　nm　with　narrow　emission-band　(about　28　nm),　and　records　high　photoluminescence　quantum　yield　(PLQY)　of　94%.　Such　a　yellow-light　emission　in　single　halide　CsPbI3　systems　has　never　been　discovered　before.　Meanwhile,　a　shallow　energy　level　in　the　OA-CsPbI3　nanowire　is　further　identified　by　the　ultrafast　transient　absorption　(TA)　and　first-principle　calculation,　which　helps　the　photoexcited　carriers　bypass　the　trap　state　level　in　the　bandgap　and　enhances　the　radiative　excitons　lifetime　with　maximum　binding　energy　up　to　212.5　meV.　What＇s　more,　the　excellent　thermal　and　moisture　stabilities　of　the　newly　formed　one-dimensional　OA-CsPbI3　nanowire　indicate　a　promising　application　prospect　in　the　field　of　luminescent　devices.