The exact cause of childhood cancer is not well understood, but nephroblastoma and retinoblastoma have been shown to be monogenic, and in addition cancers have a familial tendency to occur more frequently. Recent studies have found that there are two types of genes associated with the development of cancer, one is called oncogene and the other is called oncogene. In a normal population, these two genes are in a state of balance, but with genetic defects or under certain triggers, this balance can be disrupted, leading to the development of cancer. Most cancers in children are tumors of embryonic origin, and most affected children have hereditary factors or defects and mutations in certain genes, which often need to be triggered by external chemical, physical and biological factors. Chemical factors such as benzene, formaldehyde and radon in decoration materials are one of the important reasons to induce malignant tumors in children, in addition, parents engaged in certain toxic chemical operations such as painters, leather processing and long-term exposure to heavy metals may also increase the chance of malignant tumors in children; physical factors including exposure to ionizing radiation can increase the incidence of tumors, and even some of them will cause tumors only after several generations, such as leukemia, bone tumors, thyroid tumors, etc. Physical factors include exposure to ionizing radiation can increase the incidence of tumors, and some of them can cause tumors only after several generations, such as leukemia, bone tumors, thyroid tumors, etc.; biological factors include certain viral infections, such as EBV may cause Burkitt’s lymphoma in children, and HIV can cause Kaposi’s sarcoma and B-cell lymphoma.