The incidence of chronic heart failure (CHF) continues to escalate, imposing a tremendous burden on public health and quality of life, and has now become a leading cause of mortality globally. Mitochondrial aldehyde dehydrogenase 2 (ALDH2), a critical enzyme in aldehyde metabolism located in the mitochondrial matrix, exerts cardioprotective effects in myocardial cells by scavenging harmful aldehydes and modulating associated proteins and signaling factors. Extensive literature in recent years has substantiated its pivotal role in the initiation and progression of chronic heart failure. This article primarily provides a review of the research on the mechanisms by which mitochondrial ALDH2 operates in heart failure.