To achieve early detection and treatment, the first step is to understand thyroid cancer in children. In general, thyroid cancer grows faster, has a harder texture and uneven surface, and many patients may have metastasis of lymph nodes on the side of the neck; ultrasound examination of thyroid gland shows unclear borders, abnormal aspect ratio, poor elasticity and may show sand-like calcification foci. Xiang Mingliang, Department of Otolaryngology, Head and Neck Surgery, Shanghai Xinhua Hospital Thyroid cancer in children accounts for about 0.5%-3% of malignant tumors in children. Generally speaking, more than 90% of thyroid cancer in children is differentiated thyroid cancer. This disease does not progress rapidly and may not have any clinical manifestations in the early stages. Compared with adults, thyroid cancer in children has a lower mortality rate and a significantly better long-term survival rate than adults. However, thyroid cancer in children is multifocal in nature, i.e. there are multiple lumps in the thyroid gland, involving both lobes of the thyroid gland, and most of the primary tumors are large. It is very harmful to the growth, development, learning, and survival of children. The risk of thyroid cancer to children is also related to the degree of differentiation of the tumor. A well-differentiated thyroid cancer grows slowly, such as papillary thyroid cancer, and can survive for many years without endangering life, while a highly malignant thyroid cancer, such as undifferentiated cancer, can lead to death of the child in a short time. The overall prevalence of thyroid masses in children is significantly lower than that of adults, but the proportion of malignancy is significantly higher. The exact cause of thyroid cancer in children is unknown and may be related to abnormal exposure to radiation, excessive or deficient iodine intake, genetic factors, etc. Among them, we can see evidence that those with a family history of thyroid cancer have a significantly higher rate of thyroid cancer in their offspring. On the other hand, in the former Soviet Chernobyl nuclear leak contaminated region, the percentage of children with thyroid cancer was significantly higher than before the nuclear leak, and many of them could be traced to a history of frequent or excessive exposure to radiation. Therefore, in clinical care, many experienced physicians will try to avoid or reduce the exposure of children to radiation. The relationship between too much or too little iodine intake and the development of thyroid cancer has not been conclusively established.