In order to establish a theoretical framework for the high yield and high efficiency cultivation in the cassava/peanut intercropping system, the relationship between their roots interaction and crop competitiveness was investigated in this study. Pot experiment with three root partition treatments, completely partition(CP), partially partition(PP) and non-partition(NP) was applied to the intercropping. The aboveground dry weight of cassava and peanut, the total content of nitrogen, phosphorus and potassium, the activities of urease and acid phosphatase, the total amount of soil bacteria and fungi were measured. Cassava and peanut in CP as corresponding monoculture, the difference of partial land equivalent ratio of cassava(PLERc) or peanuts(PLERp), aggressivity, partial nutrient absorption equivalent ratio(PAERN), nutrition competitive ratio(NCR), the actual yield loss(AYL), the actual soil urease loss(ASLU), the actual soil acid phosphatase loss(ASLAP), actual soil bacteria amount loss(ASALB) and actual soil fungi amount loss(ASALF) in NP and PP were analyzed. The results showed that: ⑴ PLERc and PLERp of NP and PP were larger than 1, AYLc and AYLp were larger than 0, and PLEAc and AYLc in NP were significantly higher than in PP, while PLEAp and AYLp had no difference between in NP and in PP.⑵ Aggressivity and NCR in NP and PP were higher than 0, PAERN, PAERP and PAERK of cassava and peanut were larger than 1, PAERP and NCRP of cassava in NP were significantly higher than in PP. ⑶ASLU and ASLAP of cassava and peanut in NP and PP were higher than 0, and the value in NP were significantly higher than in PP. ⑷ASALB and ASALF of cassava in NP and PP were higher than 0, while ASALB and ASALF of peanut were less than 0, and the value in NP was significantly higher than in PP. In conclusion, promotive interaction existed between cassava and peanut roots during their intercropping mainly due to the change of microecological environment of root soil.