The double helix structure of DNA is damaged but difficult to repair, causing gene mutation, chromosome translocation, and inducing cancer. The harm to children is more obvious mainly in the following aspects: 1, the peak of growth and development, active cell division, more sensitive than adults, and the younger the younger the more sensitive. 2, the patient receives X-ray irradiation, the larger the dose, the greater the damage. 18 months of infants and young children under the greater harm. 3, children’s sensitivity to X-rays is 10 times greater than that of middle-aged people, even if a low dose of radiation will cause harm to children, girls are particularly victimized. 4, children receive more times in a short period of time X-ray irradiation, the harm is slowly accumulated. 5, the damage is mainly in three parts: reproductive glands, thyroid gland and white blood cells. 6, is the impact on children’s intelligence, according to research shows that children who have received X-ray exposure of intelligence is significantly worse than children who have not received X-ray exposure. 7. Radiation damage can lead to a variety of diseases, such as leukemia, aplastic anemia, premature aging, reproductive system diseases, cataracts, and even cancer.