Treatment of corn seeds with Bacillus subtilis strain B20-006,a potential biocontrol agent,had no effect on type of endophytic bacteria on corn.However,it stimulated endophytic bacterial reproduction in the plants.B20-006 did not affect the original population of endophytic bacteria in corn roots in early stage.In late stage,population of endophytic bacteria in corn roots treated with the bacteria was significantly higher than CK.Colonization of the bacteria in corn roots would benefit the micro-ecological resistance of cultivars against the diseases.The results suggested that strain B20006 could enhance the percentage of antagonistic endophytic bacteria against Rhizoctonia solani.The percentage in the resistant cultivar,Lianyu 11 was higher than in the susceptible one,Lianyu 13.