Abstract: Objective To investigate the the expression and clinical significance of miRNA in peripheral blood of patients with pulmonary tuberculosis,to provide reference for clinical early diagnosis. Methods From January 2012 to December 2014,30 patients with active pulmonary tuberculosis,30 patients with latent tuberculosis and 30 healthy persons in our hospital were selected as the research objects,the expression levels of miR-21-5p,miR-155-5p and miR-29a were detected in patients with active pulmonary tuberculosis (active group),latent tuberculosis (latent group) and healthy persons (control group) by reverse transcription fluorescence quantitative PCR. Results The expression levels of miR-155-5p,miR-21-5p and miR-29a were (0.43±2.11),(4.74±1.29),(3.17±0.65) in the active group,were higher than the latent group and control group(P<0.05);The expression levels of miR-155-5p was (0.96±0.28) in the latent group were higher than the control group(P<0.05);There was no significant difference in plasma miR-29a,miR-21-5p and the control group (P>0.05);The area under the miR-155-5p curve of miR-29a,miR-21-5p and ROC were 0.914,0.846 and 0.732,the sensitivity and specificity were 80% and 69.2%,73.3% and 82.9%,86.7% and 90%. Conclusion The expression of miR-155-5p,miR-21-5p and miR-29a in patients with active pulmonary tuberculosis and latent tuberculosis infection were significantly increased,which can be used as an important index for diagnosis of active pulmonary tuberculosis.