The thyroid gland is an important endocrine gland in the human body. The thyroid gland mainly secretes thyroid hormones and the body regulates the secretory function of the thyroid gland through the hypothalamic-pituitary-thyroid axis to regulate growth and development and material metabolism. The thyroid gland affects the following functions: i. It affects the body’s heat production process. Thyroid hormones can promote the increase of heat production process, and when hyperthyroidism increases heat production, there will be fear of heat and excessive sweating. Thyroid hormones can affect the metabolism of proteins, lipids and sugars, resulting in wasting and other symptoms. The lack of thyroid hormone not only affects the growth and development of the body, but also affects the intellectual development, which can lead to cretinism in children. Hyperthyroidism is characterized by reduced menstruation in women, while hypothyroidism is characterized by increased menstruation and affects male sexual function.