In　the　wastewater　treatment　processes　(WWTPs),　the　oxygen　transfer　is　a　nonlinear　and　large　time-delay　process,　which　makes　the　dissolved　oxygen　(DO)　concentration　difficult　to　control.　In　this　paper,　a　novel　kind　of　control　method　based　on　fuzzy　neural　network　(FNN)　is　proposed　for　controlling　DO　concentration.　The　parameters　of　the　neural　network　were　adjusted　online　through　the　gradient　descent　algorithm　to　get　the　minimum　error.　Finally,　the　simulation　results　in　Benchmark　Simulation　Model　No.　1　(BSM1)　show　that　the　proposed　fuzzy　neural　network　controller　has　better　adaptability　than　some　other　existing　methods.