A biological aerated filter-air flotation-sand filter process has been adopted to treat power plant wastewater.The effluent has been used as make-up water to the circulating water system.The practical operation result shows that the process has high efficiency and stability.Using this process,an effluent with turbidity ≤1 NTU,CODMn ≤5 mg /L,NH3-N ≤2 mg /L and bacteria number ≤1 000 mL-1 has been obtained.This meets the make-up water standard of circulating water systems.the experience obtained from project design and operation has been discussed.