Abstract: In order to dipose of the enviromental pollution caused by blast furnace water quenched slag and its comprehensive utilization,water quenched slag was adopted as dominating material mixed with bond and pore-forming agent by commingle,conglobate and conseve to make avoiding-burning water quenchde slag filter medium.A pilot scale Water quenched slag filter medium Biological Aerated Filter(WBAF) of 150mm in diameter and 1500mm in media height was tested to treat domestic Sewage.The results showed that ρCOD_cr=37.73 mg/L、turbidity =7.57NTU、ρ(NH₄⁺-N) 5.39mg/L when the corresponding influent concentration was 167.58mg/L、34.60NTU 、36.45mg/L,respectively,under the conditions of T=20~27℃,pH=7.0~8.0 and gas/ liquid=5∶1.The quality indexes of the domestic sewage after treatment conform with the national discharge standards.The water quenched slag filter medium has higher ammonia nitrogen removal efficiency that because it can sufficiently supply alkalinity by dissolving alkaline substances.