A　novel　porous　plastic　fiber　probe　was　developed　for　detection　of　dissolved　ammonia.　This　porous　plastic　fiber　sensitive　probe　was　prepared　based　on　the　co-polymerization　technique.　This　novel　porous　fiber　probe　has　been　used　for　determination　of　dissolved　ammonia　in　aqueous　solution　when　Erythrosin　A　was　used　as　the　fluorescent　indicator.　The　principle　and　preparation　of　this　novel　porous　fiber　probe　were　presented　in　details.　The　influences　of　polymer　materials,　the　effects　of　pH　and　the　properties　of　porous　plastic　fiber　were　also　discussed.　Experiments　revealed　that　this　fiber　probe　had　an　interconnected　porous　structure　and　high　ammonia　gas　permeability　and　water　impermeability.　In　aqueous　solution,　it　was　highly　selective　and　stable　to　dissolved　ammonia.　The　result　shows　that　the　probe　responds　to　dissolved　ammonia　over　the　linear　concentration　range　of　2.0　x　10(-4)　-9.1　x　10(-3)　mol　l(-1)　and　it　is　not　influenced　by　pH　in　solution.　(C)　2004　Elsevier　B.V.　All　rights　reserved.