Objective To establish an animal model of myocardial fibrosis induced by iron overload. Methods Eighteen Bama minipigs were randomly divided into an experimental group (n= 15) or control group (n=3). An iron dextran solution was intramuscularly injected every seven days. The first dose was 400 mg/ kg, and the other doses were 200 mg/ kg. The control group was injected with the same volume of normal saline. One to two Bama minipigs were randomly euthanized 6 days after injection of iron. Cardiac tissue sections were used for myocardial collagen volume fraction (CVF), semiquantitative myocardial iron, cardiac iron concentration (CIC) measurements. Results With the increase in the number of injections, CIC in the experimental group showed an upward trend, and the proportions of myocardial iron, and CVF (r= 0.957, r= 0.971, r= 0.957, P< 0.001). CIC was highly correlated to CVF (r=0.924, P< 0.001), and myocardial iron was highly correlated to CIC and CVF (r= 0.973, P< 0.001; r= 0.944, P< 0.001). Conclusions A miniature pig model of myocardial fibrosis was established by intramuscular injection of 400 mg/ kg iron dextran as the first dose and 200 mg/ kg iron dextran as the other doses. More iron particles deposited in the myocardium led to more severe myocardial fibrosis.