The　effects　of　molybdenum　(VI)　on　the　denitrification　efficiency　of　activated　sludge　process　were　investigated　with　batch　tests.　The　results　indicated　that　up　to　5　mg/L　of　Molybdenum　(VI)　concentrations　in　the　liquor　of　activated　sludge　process　could　accelerate　the　nitrate　removal　rate,　exhibiting　maximum　stimulation　at　1　mg/L.　Up　to　4　mg/L　of　Molybdenum　(VI)　concentrations,　the　COD　removal　efficiency　was　enhanced.　Up　to　1　mg/L　of　Molybdenum　(VI)　concentrations,　the　TTC-DHA　was　enhanced　but　higher　concentration　showed　inhibitory　effects.　Based　on　the　integrated　effects　of　Molybdenum　(VI)　on　nitrate　and　COD　removal　with　the　TTC-DHA　change,　1mg/L　of　Molybdenum　(VI)　is　proposed　as　the　best　concentration　for　denitrification　of　activated　sludge.