Abstract: Objective To investigate the application of the expression of the miR-29 family of CD4⁺ T cells and the expression of target gene IFN-γ in the diagnosis of sputum negative pulmonary tuberculosis. Methods From January to December, 2017, using convenient sampling methods, in our hospital treatment of patients with 60 cases of sputum negative pulmonary tuberculosis (negative group), 60 cases of sputum positive pulmonary tuberculosis (positive group), 35 cases of latent tuberculosis infection (infection group) were selected in our hospital physical examination and 42 healthy people for the control group were selected at the same time. CD4⁺ T cells from peripheral blood of 4 groups were separated and purified. The expressions of miR-29a, miR-29b and miR-29c in CD4⁺ T cells were detected by nucleic acid hybridization and fluorescence quantitative PCR,and the expression of miR-29 target gene IFN-γ was detected by quantitative PCR. Results The expression level of miR-29a, miR-29b and miR-29c in the negative group, positive group, latent infection group and control group in CD4⁺ T cells were different (P<0.05). The expression of miR-29b and miR-29c in negative group and positive group were higher than that in the control group, and miR-29a, miR-29b and miR-29c in the negative group, positive group were lower than the latent infection group (P<0.05); the expression level of target gene IFN-γ in the 4 groups were also different (P<0.05). Conclusion The miR-29a, miR-29b and miR-29c in CD4⁺ T cells may play an important role in the pathogenesis of phlegm negative active tuberculosis, which provides a potential target and a new strategy for the diagnosis and treatment of tuberculosis.