Abstract: SWIS as a simulation system was set up with brown meadow soil as filtering medium to monitor the changes in the concentrations of organic pollutants, nitrogen and phosphorus and investigate how the pollutants are removed at different depths of the matrix and the removal efficiency. The results revealed that the SWIS can get rid of organic matter, nitrogen and phosphorus well when the daily wastewater intake is 0.04 m³/m² and wastewater dispersion depth 55?cm, and the removal rate tends to stable with time prolonged. The sequence of pollutant removal efficiencies in accordance to the depth of matrix is Q(100)>Q(80)>Q(20)>Q(40)>Q(60), where the basic range of removing organic matter is at the depth 20~40 cm via physical-chemical adsorption and biodegradation. It was found that the nitrification mainly takes place at the depth 0~60 cm, while the denitrification plays the leading role in the region below the depth 80 cm. Based on the Langmuir adsorption model, the maximum adsorption capacity of phosphorus in brown meadow soil is 545.3 mg/kg.