Pulmonary fibrosis is a chronic, progressive and irreversible respiratory disease characterized by hyperposition of extracellular matrix leading to inflammation and extensive lung remodeling. There is currently no effective treatment. Multiple studies have shown that metformin is a classic antiglycemic drug with antifibrotic potential. However, at present, there is no consensus on the specific mechanism of metformin's anti-fibrosis effect, and this paper reviews the research progress of metformin in the field of pulmonary fibrosis in recent years, mainly from IGF-1/IGF-1R/PI3K signaling, AMPK/mTOR signaling, TGF-β/Smad signaling pathway, and intervening in myofibroblast proliferation and apoptosis, improving oxidative stress, inhibiting epithelial interstitial transformation and transglutaminase. In order to be able to more deeply and comprehensively understand the antifibrosis mechanism and clinical application scope of metformin in the future, and provide new ideas for the treatment of pulmonary fibrosis.