[Objective] To analyze the decontamination condition of urban rainwater in soil and the effect of rainwater runoff pollutants on soil environmental. [Methods] Based on full understand of soil properties and the quality of runoff in Xi'an City of Shaanxi Province

the urban soil system and rainwater runoff device were simulated to analyze the reducting functions of topsoil on rainwater runoff pollutants in the process of infiltration

and the change of the basic physical and chemical properties of soil. [Results] As the soil layer thickness was 20 cm

total rainwater penetration was 6 000 ml

and the runoff time was 3 h

the removal rate achieved above 40% both in bare soil and green fields systems on simulated rainwater pollutants. The soil density and pH value did not changed. But for the content of nitrogen

effective phosphorus

and soil organic matter

from in the original soil to green fields and bare soil

they changed from 54.95 mg/kg to 65.10 mg/kg and 68.60 mg/kg

59.23 mg/kg to 82.39 mg/kg and 39.93 mg/kg

18.32 mg/kg to 19.28 mg/kg and 14.04 mg/kg

respectively. [Conclusion] The effect of green fields on runoff water treatment is significant. In the process of infiltration

soil present significant effect on removal of ammonia nitrogen

and soil basic physical properties show little change within a short time.