The paper carried out advanced purification experiment on both simulated wastewater and the secondary effluent of a wastewater treatment plant in Xi'an by applying biological slow filter pool. The purification effect was evaluated through the analysis of nitrogen, phosphorus contents and potassium permanganate indices in the influent and effluent as well as chlorophyll a content in the overlying water and effluent. The results suggested that biological slow filter showed better treatment performance on simulated sewage and the removal rate of total nitrogen, ammonia nitrogen, total phosphorus and potassium permanganate index is 66.4%, 40.2%, 66.4% and 73.3% respectively;the removal rate of the secondary effluent of a wastewater treatment plant to which is 35.1%, 21.0%, 30.2% and 12.6%,the removal rate is lower than that of manual simulated test.Moreover, biological slow filter has good retention effect to chlorophyll a, the removal rate is 93.4% and 66.4% respectively. The quality of the reclaimed water treated by the biological slow filter reaches the requirements of water quality standard for scenic environment use.Therefore, the reclaimed water can be re-used as urban landscape water body and prevent the occurrence of eutrophication.