In　this　article,　a　soluble　poly[2-methoxy-5-(3＇-methyl)　butoxy]-p-phenylene　vinylene　(MMB-PPV)　was　synthesized　by　dehydrochlorination　reaction　and　the　MMB-PPV　film　was　implanted　by　nitrogen　ions　(N+)　with　the　ion　dose　and　energy　in　the　range　of　3.8　x　10(15)　to　9.6　x　10(16)　ions/cm(2)　and　15-35　keV,　respectively.　The　surface　conductivity,　optical　absorption,　optical　band　gap　(E-g)　of　modified　MMB-PPV　film　were　studied,　and　the　third-order　nonlinear　optical　susceptibility　(chi((3)))　as　well　as　its　environmental　stability　of　modified　MMB-PPV　film　were　also　measured　by　degenerate　four-wave　mixing　system.　The　results　showed　that　the　surface　conductivity　of　MMB-PPV　film　was　up　to　3.2　x　10(-2)　S　when　ion　implantation　was　performed　with　the　energy　of　35　keV　at　an　ion　dose　of　9.6　x　10(16)　ions/cm(2),　which　was　seven　order　of　magnitude　higher　than　that　of　the　pristine　film.　UV-Vis　absorption　spectra　demonstrated　that　the　optical　absorption　of　MMB-PPV　film　was　enhanced　gradually　in　the　visible　region　followed　by　a　red　shift　of　optical　absorption　threshold　and　the　E-g　value　was　reduced　from　2.12　eV　to　1.59　eV　with　the　increase　of　ion　dose　and　energy.　The　maximum　chi((3))　value　of　2.45　x　10(-8)　esu　for　modified　MMB-PPV　film　was　obtained　with　the　ion　energy　of　20　keV　at　an　ion　dose　of　3.8　x　10(16)　ions/cm(2),　which　was　almost　33　times　larger　than　that　for　pristine　film.　In　comparison　to　the　reduction　of　17%　in　the　chi((3))　value　of　pristine　MMB-PPV　film,　the　maximum　chi((3))　value　of　2.45　x　10(-8)　esu　for　modified　MMB-PPV　film　decreased　by　over　5.3%　when　they　had　been　exposed　under　the　same　ambient　conditions　for　90　days.　(C)　2010　Wiley　Periodicals,　Inc.　J　Polym　Sci　Part　B:　Polym　Phys　48:　2072-2077,　2010