In recent years, due to the improvement of people’s living standard and the strengthening of national prevention of childhood diseases, the morbidity and mortality of infectious diseases and malnutrition have been significantly reduced. Malignant tumors have now become one of the main factors threatening the life and healthy growth of children besides trauma, which should attract the attention of the whole society. Unlike adult tumors, malignant tumors in children can occur at all ages, some of them can be found in fetal stage, and the pathological types are mostly embryonic tumors. The causes are not clear yet, but many studies at home and abroad show that the occurrence of many tumors are related to genetic changes and heredity. Children’s tumors are fast growing, easy to metastasize early, short course and high malignancy, but most of them are sensitive to chemotherapy and radiotherapy, and the treatment effect is significantly better than that of adults. At present, the overall cure rate of childhood tumors has reached 60%. Common clinical malignant tumors in children include leukemia, brain tumors, malignant lymphoma and other solid tumors such as nephroblastoma and neuroblastoma. Changes in treatment mode of pediatric tumors For a long time, due to the low incidence of pediatric tumors compared with adult tumors and the lack of concentration of cases, there are fewer hospitals and medical personnel specializing in pediatric tumors, and it is difficult to formulate more unified treatment standard, resulting in the uneven treatment level in different places. As most pediatric tumor patients are treated in general hospitals, it is inevitable that surgery is only responsible for surgery and internal medicine is only responsible for chemotherapy, which makes the treatment process lack systematic and coherent. In addition, many patients’ families and medical personnel do not know enough about childhood tumors, and there is a misconception that surgery plays a decisive role in the treatment of tumors, while ignoring the role of other treatments, and once the tumors are found, they will strive for surgery as soon as possible, or even blindly carry out exploration. However, if the tumor is large or adheres to important organs, it will not only be unable to be completely removed but also may lead to the spread of tumor and postoperative complications, which will cause difficulties in further treatment and thus affect the efficacy. Pre-operative diagnosis, evaluation and systematic treatment plan of the child: The child should undergo comprehensive imaging, blood and immunological tests, and if necessary, bone marrow and cerebrospinal fluid aspiration and ultrasound-guided aspiration biopsy or surgical excision to confirm the diagnosis as soon as possible. Based on the results of the above tests, we will analyze the progress of the disease and judge the prognosis of the child, and determine the accurate clinical staging according to the international standard, such as NWTS-V for nephroblastoma and EVANS for neuroblastoma, and formulate the corresponding systematic treatment plan accordingly. Preoperative adjuvant therapy and timing of surgery: Most of the malignant tumors in children are more sensitive to chemotherapy and radiotherapy, so preoperative adjuvant chemotherapy and radiotherapy can be adopted. After years of clinical practice, it has been proved that preoperative adjuvant therapy has many advantages: firstly, it can shrink and confine the tumor, so that the original unresectable tumor can be completely removed and the surgical resection rate can be improved; secondly, it can reduce the activity of tumor cells, necrosis, calcification and fibrosis in different degrees inside the tumor, and reduce the spread of tumor cells due to compression of the tumor during surgery; thirdly, it can relatively narrow the scope of surgery and reduce the risk of surgery. Thirdly, it can relatively reduce the scope of surgery, decrease the risk of surgery, reduce the degree of limb and organ damage caused by extensive removal of tumor, and ensure its survival quality as much as possible. Therefore, it is important to avoid blind surgical investigation after tumor discovery, to master the timing and indications of surgery, to strive for complete resection of tumor, and to avoid tumor spreading or treatment failure caused by improper surgery. Through the second-stage surgery after preoperative chemotherapy, we have successfully resected many cases of giant hepatoblastoma, nephroblastoma and other giant tumors in the chest and abdomen, head and neck and limbs. 3. Determination of post-operative pathological type: The post-operative specimens are examined by pediatric oncology pathologists for light microscopy, immunohistochemistry and molecular biology to determine the detailed and accurate pathological type so that the corresponding chemotherapy and radiotherapy plans can be adopted. 4. Postoperative formal treatment and disease monitoring: Postoperative formal radiotherapy and chemotherapy are very important in the treatment of pediatric tumors. With the increase of chemotherapy drugs, the update of radiotherapy equipment and the strengthening of symptomatic management of radiotherapy and chemotherapy reactions, most children can complete the regular course of treatment as long as the indications and doses are mastered, and the radiotherapy and chemotherapy reactions are prevented and treated in a timely and correct manner. The chemotherapy regimens we currently adopt, such as malignant lymphoma, rhabdomyosarcoma, nephroblastoma, neuroblastoma, etc., all adopt the latest domestic and foreign regimens and have achieved more satisfactory results through clinical observation. In the course of postoperative treatment, specific blood and immunological indicators and imaging are regularly reviewed and monitored to determine the progress of the disease and to make appropriate adjustments to the treatment plan. 5. Application of interventional therapy and intraoperative radiotherapy in clinical treatment: Some huge tumors of liver and kidney can be treated by interventional therapy through femoral artery cannulation when they cannot be removed surgically or when the sensitivity of systemic chemotherapy is poor, so that the therapeutic effect can be improved. 6. Application of immunotherapy: As the main adjuvant therapy, immunotherapy has been gradually applied in the treatment of childhood malignant tumors, such as interferon, interleukin-II, differentiation inducer of neuroblastoma, etc. It can achieve certain therapeutic effects by controlling the differentiation and proliferation of tumor cells, inducing apoptosis of tumor cells and regulating the patient’s own anti-tumor immune function.