【Abstract】 Subclinical hypothyroidism, the mildest form of the hypothyroidism, is middle state between health and clinical hypothyroidism. With the development of the modern science and technology and improvement of the people health consciousness, detection rate of the SCH has significantly increased. A growing number of studies have shown that subclinical hypothyroidism increases the incidence of cardiovascular disease. This article first reviews thyroid hormone as it relates to the cardiovascular system and then discuss SCH, its association with cardiovascular risk factors and cardiovascular disease, and an approach to its treatment.