In order to understand the effects of the application of extra actinobacteria on the growth of foxtail millet and culturable microorganisms in rhizosphere soil at the mature stage, pot and field experiments were conducted to study the differences in the biomass and yield formation of foxtail millet and the culturable microorganism structure in rhizosphere soil at the mature stage after Streptomyces albidoflavus (T4) and Streptomyces pactum (Act12) application, and the relationship between the growth of foxtail millet and soil microorganisms were also investigated. Results show that the biomass of foxtail millet is increased under T4 both in the pot and field trials, while the grain weight of single plant and the yield of foxtail millet are increased by 13.7%-22.6% under T4 and Act12 in the field trial than that of the control. The population of bacteria (B), fungi (F), actinobacteria (A), and total of microorganisms are increased by 29.5%-56.9% under T4 in the light incubator pot trial. The population of fungi is increased by 73.3% and 222.0% respectively under T4 and Act12 in outdoor pot trial compared with the control, while the population rates A/F and B/F are reduced by 34.7%-72.4%. The stem and leaf dry weights and the grain weight of single foxtail millet plant at the mature stage are positively correlated with the population of B, F, A and the total population of the culturable microorganisms in the rhizosphere soils (r=0.748-0.971, P<0.01), whereas negatively correlated with A/F and B/F (r=-0.764- -0.906, P<0.01). In conclusion, the tested actinobacteria can promote the growth and yield of foxtail millet through adjusting soil culturable microbial environment, thus, the application of extra actinobacteria to optimize the culturable microorganism structure in rhizosphere soil is a useful measure to promote foxtail millet growth.