In　this　study,　coagulation　condition　and　prechlorination　on　membrane　fouling　were　investigated.　Optimum　operation　parameters　of　overall　process　were　obtained　through　a　proposed　combined　process　of　coagulation　and　ultrafiltration　(UF)　with　the　prechlorination　unit　set　after　the　coagulation　unit　and　before　the　UF　unit.　Effects　of　velocity　gradient　of　the　coagulation　unit　and　the　dosage　of　NaClO　on　the　range　of　workable　flux　and　water　purification　were　assessed　using　response　surface　methodology.　The　range　of　workable　flux　of　UF　module　obtained　under　an　agitator　rotational　velocity　of　40rpm　in　the　coagulation　unit　represented　the　maximum　one.　Removing　as　much　organic　contaminants　as　possible　is　the　key　to　alleviating　membrane　fouling.　The　proposed　process　does　not　require　use　of　the　prechlorination　unit　and　is　not　necessary　and　suitable　for　treatment　of　this　type　of　raw　water.　Higher　velocity　gradient　and　operating　flux　presented　a　slower　rate　of　filtration　resistance　growth.　Optimum　values　of　40rpm,　0mg/L,　and　100　L/[m(-2)　h]　were　obtained　for　the　agitator　rotational　velocity,　NaClO　dosage,　and　operating　flux,　respectively.　Under　this　condition,　the　specific　flux　decay　rate　reached　the　minimum　value　during　a　single　filtration.