Positron emission tomography (PET) plays an important role in the diagnosis and treatment of heart diseases. Using specific tracers, cardiac PET imaging can reveal various pathophysiological processes such as myocardial blood flow perfusion, metabolic activity, and inflammatory responses. It is widely used in the diagnosis and treatment of coronary artery disease, cardiac sarcoidosis, cardiac amyloidosis, heart failure, and also plays a significant role in assessing myocardial fibrosis. This article reviews the physical basis of cardiac PET imaging, the main types of tracers, and their applications in heart disease. With technological advancements, cardiac PET imaging is expected to play an increasingly critical role in the diagnosis and management of heart diseases.