Abstract: Strains A01 and A64 are two actinomyces isolated from stevia rhizosphere which showed a high growth rate and strong antibiosis activity and these 2 strains kept their high growth rate and stable antibiosis activity. Taxonomy identification suggested that these two isolates are members of Streptomyces Waksman and Henrici. A01 belongs to yellow group, and A64 is an isolate of blue group. Application of biocontrol agents on stevia leaves could effectively suppress the leaf spot disease. The average control effect was 56.3%. Mixture of A01 and A64 showed a significantly enhanced biocontrol effect compared with the individual isolates. The average yield increasing was 18.7%, especially in the mono-cropping area, yield increasing was more distinct.