The fermentation broth and mycelium pellet of Streptomyces pactum Act12 (Act12) may promote the accumulation of soluble sugar when added to Salvia miltiorrhiza hairy roots, increasing the accumulation level by as much as 23.20 % compared with the control; it may also inhibit the accumulation of soluble protein in the hairy roots, decreasing it by as much as 17.96 % compared with the control. The ACT12 also has a certain promotional effect on the growth of hairy root at an appropriate concentration of elicitors and upregulates the expression of genes 3-hydroxy-3-methyglutary1-CoA reductase (HMGR), 1-deoxy-d-xylulose 5-phosphate synthase (DXS), 1-deoxy-d-xylulose-5-phosphate reductoisomerase (DXR), and geranylgeranyl diphosphate synthase (GGPPS). Among these effects, that of the HMGR gene expression is as high as 33.66 times that of the control, indicating that the test Streptomyces pactum may efficiently adjust the secondary metabolism of S. miltiorrhiza at the level of gene transcription, thereby greatly increasing the accumulation level of tanshinone in the hairy roots; among which, the cryptotanshinone levels increased most significantly, as much as 33.63 times that of the control, and the total tanshinone levels were 12.61 times that of the control.