Based　on　the　near-field　optical　theory,　the　near-field　characteristics　of　Ag　nanoparticle　within　the　near-field　scope　of　a　metallic　AFM　tip　irradiated　by　optical　fiber　probe　laser　are　carried　out　with　finite　element　method.　As　the　laser　transmits　in　optical　fiber　probe,　the　light　of　the　various　modes　is　gradually　turned　off,　remaining　the　HE11　mode　laser.　Meanwhile,　the　evanescent　field　can　be　produced　at　the　confined　aperture,　which　will　also　stimulate　the　near-field　enhancement　phenomenon　of　metallic　AFM　tip　and　Ag　nanoparticle　with　those　extrema　appearing　in　the　apex　of　AFM　tip,　the　upper　and　lower　parts　of　Ag　nanoparticle,　and　the　upper　and　lower　sharp　boundary　positions　at　the　end　of　the　tapered　fiber　probe.　The　related　mechanism　is　revealed　and　near-field　optical　characteristics　are　also　analyzed.