Pulmonary fibrosis is a kind of disease caused by various factors that result in the change of fibroblasts, including their activation along with differentiation into myofibroblasts, and the generation and deposition of the extracellular matrix, which eventually leads to functional failure. Currently, there is a lack of effective treatment. However, current studies have found that microRNA-133a (miR-133a) can regulate the transforming growth factor-β (TGF-β) signaling pathway, thereby inhibiting pulmonary fibrosis, which provides a new target for the treatment of pulmonary fibrosis. In the future, miR-133a can be studied to explore its specific role in the human TGF-β signaling pathway, so as to provide a new direction for the treatment of pulmonary fibrosis.