Abstract: Removal effects of DOC and A₂₅₄ are investigated with pretreatment processes of sand filtration, fibrous filtration,coagulation-sand filtration and coagulation-fibrous filtration combined with ultrafiltration, compared with direct ultrafiltration under pilot scale.Influence of organic matter removal of ultrafiltration is probed by various pretreatment processes.Results show that effects of organic matter removal can be enhanced by the pretreatment processes.A₂₅₄ removal rate of ultrafiltration outlet is raised 16,7,23 and 14 percentage points and DOC removal rate of ultrafiltration outlet is raised 17,14,27 and 19 percentage points,with pre- treatment of sand filtration,fibrous filtration,coagulation-sand filtration and coagulation-fibrous filtration, compared with direct ultrafiltration.The organic matter removal effect and stabilization of coagulation-sand filtration process is better than other process.It is highly effective to improve membrane treatment efficiency and membrane contamination protection apply DOC and A₂₅₄ indexes of treated water by ultrafiltration are improved clearly.The best effect is achieved by coagulation-sand filtration process.The coagulation process is showed remarkable contribution to DOC and A₂₅₄ removal.