[Objective] The factors affecting the reduction of pollutants by improved green space media were analyzed, in order to provide a scientific reference for the construction of green space in sponge cities.[Methods] This experiment investigated the pollutant retention characteristics of urban green space[soil:sand:coir (4:4:2) + 1% PAM] under the combined influence of the repetition period of rainfall, leaching time and depth through indoor simulation experiments, with a view to providing some reference for greenfield construction in sponge cities.[Results] The main factors affecting the different pollutant types in the modified media varied depending on the pollutant type. Among them, the depth factor had a greater contribution to the leaching concentration of nitrogen and COD, and the repetition period of rainfall had a greater contribution to the leaching concentration of phosphorus. The decreasing trend of nitrogen and COD leaching concentration over time could be expressed by a power function or an exponential function. Phosphorus leaching concentration changed with time, showing a trend of first decreasing and then increasing. The overall leaching concentration of nitrogen and COD showed an increasing trend with the increase of the repetition period of rainfall and substrate depth. The phosphorus leaching concentration showed an increasing trend with the increase of the repetition period of rainfall, and showed a decreasing trend with the increase of the depth. On the whole, soil mixed with sand and coir (4:4:2) + 1% PAM had a stronger ability to reduce phosphorus, but a weaker ability to reduce nitrogen and COD.[Conclusion] Soil mixed with sand and coir (4:4:2) + 1% PAM improved medium can effectively intercept phosphorus pollutants in rainwater, and can be used in the construction of sponge urban green space.