Abstract: Taking the ginseng in Xiao Xing’an Mountains of Northeast China as test object, this paper studied the effects of applying Streptomyces pactum (Act12) on ginseng growth and on the soil microflora in root zone and root surface. After treated with Act12, the yield and quality of ginseng’s medicinal part improved, the induced enzyme activities in leaves and the root activity increased, and the numbers and proportions of soil bacteria and actinomycetes increased significantly while those of soil fungi decreased.  Compared with the control, the soil microflora in treatment Act12 changed. The numbers of the dominant bacteria Pseudomonas fluorescens, Pseudomonas koreensis, and Microbacterium oxydans were much higher in root zone soil and root surface soil, and the pathogen Plectosphaerella cucumerina decreased in root zone soil and disappeared in root surface soil. These results suggested that the addition of Act12 could improve the soil microflora, enhance the resistance and root activity of ginseng plant, and increase the ginseng yield and its quality.