Children of chromosomally normal parents may have chromosomal abnormalities. The parents are chromosomally normal, but it does not mean that the sperm is chromosomally normal and the egg is chromosomally normal. During the development of the fertilized egg, the child’s chromosomes may also undergo mutations and translocations due to environmental pollution, advanced age of the pregnant woman, smoking and alcohol abuse by the pregnant woman, and exposure of the pregnant woman to large doses of radioactive chemicals and toxic drugs, causing chromosomal abnormalities in the child. The occurrence of chromosomal diseases in children has a certain relationship with the parents’ chromosomes, and is also related to the surrounding environment. Chromosomes in early pregnancy are easily affected by the external environment, leading to the occurrence of chromosomal diseases in children. During pregnancy, attention should be paid to avoiding viral infections, avoiding oral medications that can lead to fetal malformations, and regular prenatal checkups to reduce the likelihood of chromosomal disorders. Pregnant women during pregnancy should improve all kinds of prenatal screening under the guidance of doctors, try to detect fetal chromosomal abnormalities. Pregnant women should pay attention to avoid contact with toxic and harmful substances during pregnancy to reduce the probability of chromosomal diseases.