Selecting cassava monocrop and cassava - Arachis pentoi intercrop systems from 9 different cultivation systems to study the properties of root space variety and soil quality change. The results indicated that there were 86. 8 % and 91. 1 % roots to distribute in the layer of 0 - 40 cm for the cassava monocrop and cassava intercrop systems, respectively. The root biomass of cassava intercrop was 55. 4% greater than that of the cassava monocrop. The coverage of cassava intercrop had been increased by 56. 8% and reduced soil loss 4 times than that of cassava monocrop. The cassava intercrop system was able to improve nutrient uptake by cassava, and get higher nutrient content in the aboveground plant. The cassava intercrop not only improved potassium acquisition by cassava, but also increased available nutrient in each layer and enhanced the capacity of soil nutrient supplying and soil quality.