Hashimoto’s thyroiditis, also known as chronic lymphocytic thyroiditis, was first reported by the Japanese scholar Hashimoto in 1912. Hashimoto’s thyroiditis is the most common cause of hypothyroidism, with an annual increase of 5%, and is most common in women aged 30 to 50. The clinical manifestations of Hashimoto’s thyroiditis can be divided into early (hyperthyroidism), middle (hyperthyroidism and hypothyroidism) and late (hypothyroidism) stages. Patients with long-term Hashimoto’s thyroiditis generally have a significant decrease in thyroid function, which affects their normal life. There is no specific treatment for Hashimoto’s thyroiditis, and modern medical treatment is limited, but surgery is generally not indicated. After clinical diagnosis, treatment should be determined by the size of the thyroid gland and the presence or absence of symptoms of compression. If the thyroid gland is small and there are no obvious symptoms of pressure, it can be followed up without treatment, but if the thyroid gland is obviously enlarged and has symptoms of pressure, it should be treated. Thyroid hormones play an important biological role in the growth and development of the body, material metabolism, and the function of target organs, and a deficiency of thyroid hormones will cause great damage to the normal physiological function of the patient, so active treatment is necessary. The main treatment for hypothyroidism in Hashimoto’s thyroiditis is currently pharmacological, with selenium yeast and eugenol being two commonly used drugs. Recent studies have shown that selenium plays an important role in the thyroid tissue, and the normal secretory function of the thyroid gland depends on the proper amount of selenium, and selenium supplementation can significantly increase thyroid hormone and decrease thyroid stimulating hormone. In this study, we showed that the serum F3 and F4 values increased significantly and TSH values decreased significantly after the treatment of hypothyroidism in Hashimoto’s thyroiditis with selenium yeast adjuvant eugenol, which was better than the control patients, and the serum thyroid autoantibody level decreased significantly, which showed a significant therapeutic effect. Lei Yonghong et al. confirmed that the treatment efficiency of selenium combined with methimazole pills and methimazole group was 82.8% better than that of methimazole alone, methimazole combined with methimazole pills and selenium combined with methimazole group, and FT3, FT4, TG=Ab and TPO-Ab decreased the fastest, and goiter and proptosis improved the best, which is basically consistent with the results of this study. The results were consistent with the results of this study. In conclusion, for patients with hypothyroidism in Hashimoto’s thyroiditis, the combination of selenium yeast and methimazole can effectively improve the serum thyroid hormone-related indexes and reduce the autoantibodies of the thyroid gland, which can alleviate the symptoms of hypothyroidism and improve the autoimmune condition of patients.