Hashimoto's thyroiditis refers to the destruction of thyroid tissue by autoimmune cells. Therefore, during the course of the disease, three states of thyroid function can be manifested: hyperthyroidism, euthyroid state, and hypothyroidism. When the patient presents with hyperthyroidism, it is possible to treat with anti-thyroid drugs, but the dosage of the anti-thyroid drugs should be reduced. When thyroid function is normal, no special treatment is needed, and regular thyroid function testing is sufficient. When there is concurrent hypothyroidism, thyroid hormone replacement therapy is required to achieve clinical healing.