In recent years, thyroid cancer has become the fastest growing malignant tumor in China, with an incidence rate that has increased nearly five times in 10 years. The distribution of thyroid cancer in China is the highest in the east and the lowest in the central part of the country. Although the exact cause of thyroid cancer is unclear, ionizing radiation, iodine intake, estrogen and genetic factors are all risk factors for thyroid cancer. Iodine intake is related to the occurrence of thyroid gland and its pathological type. Iodine is an essential trace element for human body, and iodine deficiency can lead to decrease in synthesis and secretion of thyroid hormone and increase in thyroid stimulating hormone (TSH) level, which can lead to thyroid follicular hyperplasia and even nodules or cancer. However, studies have found that the incidence of thyroid cancer is equally high in areas with high iodine levels, and all of them are papillary carcinomas. Excess and excess iodine intake can trigger and promote the development of hypothyroidism and autoimmune thyroiditis. Excessive iodine intake can lead to an increase in thyroid disease and a consequent change in the distribution of pathological types of thyroid cancer, with an increase in papillary carcinoma and a decrease in follicular carcinoma. Therefore, the correct approach is to consume iodized salt or moderate intake of iodine-rich foods such as seaweed and seaweed to ensure the physiological requirements, and neither “too much” nor “not enough” is desirable. Exposure to ionizing radiation is a relatively clear risk factor for thyroid cancer. Radiation from nuclear power plants or nuclear weapons and some medical examinations are the main sources of ionizing radiation. (1) A Chinese study on cancer incidence and risk assessment of medical radiologists showed that the risk of thyroid cancer was associated with occupational exposure to X-rays. (2) History of head and neck radiation exposure during childhood and history of whole body radiation therapy have been clearly identified as causative factors for thyroid cancer. (3) Several studies in recent years have confirmed that children undergoing dental surface tomography for various dental disorders increase the incidence of thyroid cancer by nearly twofold. The younger the child is, the higher the risk of thyroid cancer after receiving head and neck irradiation. Therefore, children with a history of head and neck irradiation should be followed up with long-term thyroid ultrasound. The physician should also evaluate the need for radiological examination or treatment in a comprehensive manner to minimize unnecessary irradiation. If the examination is necessary, the protection of the thyroid gland during the examination should be emphasized, such as the application of protective measures such as lead collars.