To study the jamming effects of RNAi hairy roots of Salvia Miltiorrhiza by in situ infection of soil cultivating plants.Methods:Hairy roots were induced by infection of Agrobacterium rhizogenes transformed with the RNAi vector of target gene into the roots of Salvia Miltiorrhiza which were planted in the soil.Positive hairy roots were identified by fluorescence microscope.The expression of target gene was detected by qRT-PCR analysis.Results:Hairy roots were induced from the roots of Salvia Miltiorrhiza successfully.GFP detection results showed that positive conversion rates of hairy root lines of target gene RNAi and empty vector were 72.72% and 66.7%,respectively.qRT-PCR analysis revealed that the expression of target gene in RNAi hairy roots was significantly decreased to 8.61% compared with empty vector,which indicated that RNAi hairy roots were successfully induced from the soil planted Salvia Miltiorrhiza by in situ infection.Conclusion:Positive target gene-RNAi Salvia Miltiorrhiza hairy roots were successfully induced from the soil planted Salvia Miltiorrhiza by in situ infection.As the infection required no sterile operation,it was not only simple and quick,but also would not affect plant growth and development.It can be applicable to functional characterization of gene in vivo.