Chemotherapy is a very effective treatment in the treatment of malignant tumors, which can be administered intravenously and orally. Chemotherapy will produce certain toxic side effects on patients, mainly reflected in the digestive system, bone marrow suppression, specific toxicity and so on. 1. Digestive system: digestive symptoms are the most common side effects of chemotherapy, mainly manifested as stomach pain, bloating, nausea, vomiting, abdominal pain, diarrhea, loss of appetite and so on. 2. Bone marrow inhibition: chemotherapeutic drugs can kill normal cells while killing tumor cells, which has inhibitory toxic side effects on bone marrow, mainly manifested as reduction of white blood cells, leading to decreased immunity, reduction of red blood cells, leading to different degrees of anemia, fatigue, platelet reduction, mild reduction with no obvious symptoms, and in severe cases, petechiae will appear under the skin, or even massive hemorrhage. 3. Specific toxins: some chemotherapy drugs have ototoxicity, cardiotoxicity, nephrotoxicity, peripheral neuropathy and other toxic side effects. Therefore, patients with malignant tumors need to rationally apply chemotherapy programs under the guidance of specialists, consult the doctor in time when toxic side effects occur, adjust the treatment plan if necessary, and treat the symptoms to reduce the pain caused by chemotherapy.