Thrombotic diseases are a major threat to human health, ranking first in causes of death worldwide. Endothelial nitric oxide synthetase ( eNOS) is the main source of nitric oxide, an important protective factor of the cardiovascular system. As an important bioactive substance protecting the vascular wall, eNOS participates in the pathophysiological processes of thrombotic diseases such as acute coronary syndrome, atrial fibrillation, stroke, pulmonary thromboembolism and deep vein thrombosis. This paper reviews the structure and physiological functions of eNOS, its mechanisms, and research progress in thrombotic diseases.