Abstract: Myocardial fibrosis is characterized by abnormal deposition of non-contractile extracellular matrix in myocardium. Under various pathophysiological conditions, myocardial fibrosis can cause cardiac systolic and diastolic dysfunction, which is the main pathological manifestation in a variety of cardiovascular diseases. It destroys the structure of myocardium, disturbs the coupling of excitation and contraction of myocardium, damages its systolic and diastolic functions and induces arrhythmia and cardiac dysfunction, thus aggravating heart disease, eventually leading to heart failure and affecting the clinical process and outcome of patients with heart failure. At present, a number of studies have shown that there are many pathogenic factors of myocardial fibrosis, but the specific pathological mechanism of its occurrence and development is not clear and needs further research and exploration. Studies have shown that inflammatory cytokines and chemokines, reactive oxygen species, renin–angiotensin-aldosterone system, matrix proteins and growth factors are closely related to myocardial fibrosis. This article is a review of the research progress in the mechanism and the treatment of myocardial fibrosis.