Thyroid disease is one of the common causes of recurrent spontaneous abortion (RSA), and it is involved in the occurrence of RSA mainly from the endocrine and immune levels. Abnormal thyroid hormone levels and the presence of anti-thyroid autoantibody (ATA) can affect the normal physiological changes of the mother and embryonic development during pregnancy, leading to abortion. For RSA patients with abnormal thyroid dysfunction, diagnosis and treatment should be given before pregnancy, and pregnancy should be considered when thyroid function is normal. For RSA patients with normal thyroid function but with positive ATA, the use of levothyroxine before pregnancy remains controversial.