The rat models of pulmonary tuberculosis were established by injecting Mycobacterium tuberculosis suspension through tail vein， after successful modeling， the model rats were randomly divided into model group， miR-27a agomir control （agomir-NC） group and miR-27a agomir （agomir） group，and another normal rats were used as control group； there were 12 mice in each groups.The rats in agomir-NC group or miR-27a agomir group were injected with agomir-NC or miR-27a agomir via tail vein once a day for 5 consecutive days. Three weeks later，the spleen and thymus indexes of the rats in various groups were calculated， the pathomorphology of lung tissue of the rats in various groups were observed by HE staining； the percentages of T lymphocyte subsets in peripheral blood of the rats in various groups were detected by flow cytometry； the levels of interleukin-1β （IL-1β）， interleukin-6 （IL-6） and tumor necrosis factor-α （TNF-α） in lung tissue of the rats in various groups were determined by enzyme linked immunosorbent assay （ELISA）； the expression levels of miR-27a in lung tissue of the rats in various groups were detected by real-time fluorescence quantificative PCR （RT-qPCR） method； the expression levels of Toll-like receptor 4 （TLR4）， nuclear factor kappa-B （NF-κB） inhibitor α （IκBα）， phosporylated-IκB（p-IκB） and NF-κB p65 in lung tissue were detected by Western blotting method.

Compared with control group，the lung injury of rats in model group was serious， the spleen and thymus indexes， the percentages of CD4+T cells in peripheral blood， the expression level of miR-27a and the expression level of IκB protein in lung tissue were significantly decreased （P<0.05）； the percentages of CD8+T cells in peripheral blood， the levels of IL-1β， IL-6， TNF-α and the expression levels of TLR4， p-IκB and NF-κB p65 proteins in lung tissue were significantly increased （P<0.05）. Compared with model group， the pathomorphology of lung tissue of the rats in agomir group was significantly improved， the spleen and thymus indexes，the percentages of CD4+T cells in peripheral blood， the expression level of miR-27a and the expression level of IκB protein in lung tissue were significantly increased （P<0.05）； the percentage of CD8+T cells in peripheral blood， the levels of IL-1β， IL-6， TNF-α and the expression levels of TLR4， p-IκB and NF-κB p65 proteins in lung tissue of the rats were significantly decreased （P<0.05）； there were no statistically significant differences in the above indexes of the rats in agomir-NC group （P>0.05）.

Overexpression of miR-27a may improve the lung injury in the pulmonary tuberculosis rats by inhibiting activation of TLR4/NF-κB signaling pathway， reducing the release of inflammatory factors and regulating the body's immune response.