Abstract: Langerhans' cell histiocytosis is a kind of uncommon disease , involvement of the thyroid by langerhans' cell histiocytosis is rare. 2 cases of Langerhans cell histiocytosis of the thyroid confirmed by pathology were reported in the paper. The main clinical represent was the enlargement of the thyroids. One patient had hypothyroidism. Meanwhile, the lungs and pituitaries of the two patients were affected. Langerhans' cell histiocytosis of the thyroid has no typical symptoms and specific laboratory examination, and can be clinically confused with chronic lymphocytic thyroiditis, benign and malignant thyroid tumors. Thyroid fine needle aspiration cytology may be useful in making the diagnosis. The effective treatments include systemic chemotherapy, local radiation therapy and surgical excision. The chemotherapy is still the main approach. Most patients can relieve partially after receiving the systemic chemotherapy.