Disclosed in the present invention is use of meroterpenoid I in preparation of an anti-heart failure drug. In the present invention, mouse heart failure models induced by doxorubicin or left anterior descending coronary artery ligation are treated with meroterpenoid I isolated and purified from marine fungus Aspergillus terreus GZU-311. It is found that the meroterpenoid I can improve cardiac function in mice, reduce cardiomyocyte injury, inhibit myocardial connective tissue thickening, ameliorate disordered arrangement of cardiomyocytes, and reduce inflammatory cell infiltration, thereby exhibiting an anti-heart failure effect. Therefore, the present invention provides the use of meroterpenoid I in the preparation of an anti-heart failure drug. The present invention enriches pharmaceutical molecules available for the treatment of heart failure, thereby facilitating the development of anti-heart failure drugs and their clinical treatment.