Abstract: Through artificial rainfall simulation, the farming soil structure and infiltration, water and sediment yields were studied under different slopes from 0° to 20° and different contents of fly-ash from 0 to 10%. Results show that with the increase of fly-ash content in the farming soil, the soil infiltration rate accelerates obviously. The infiltration rate of farming soil with fly-ash of 10% improves by 55.34% than that of the contrast(soil without fly-ash). The soil bulk density decreases and the soil porosity increases after adding fly-ash. Compared with the contrast, the bulk density of farming soil with fly-ash of 10% reduces by 17.42%, and the porosity improves by 9.84% at 10° slope. The runoff yield and soil losses decrease. The runoff yield of farming soil with fly-ash of 10%, accounts for 26.87% of that of the contrast at 20° slope. Therefore, after exerting 10% fly-ash in the cultivated soil layers, the soil structure can be improved effectively, and the runoff and sediment are intercepted, which have higher practical value.