Chemotherapy can be carried out three weeks to six weeks after open-heart surgery for lung cancer. Lung cancer is a more common lung malignant tumor nowadays, surgery combined with radiotherapy can play a good therapeutic effect. If the patient’s body recovers better after surgery and can tolerate a series of reactions brought by chemotherapy, chemotherapy can be feasible to be assisted in three weeks after surgery. However, if the patient’s recovery time is longer and the body is difficult to tolerate, it can be extended to four weeks to six weeks. It should be noted that, even if the patient’s physical condition has not reached a completely ideal state, the time to start chemotherapy after surgery should not be too long, otherwise the efficacy of the treatment will be affected. During the period of chemotherapy, we should pay attention to observe whether there are adverse reactions, including digestive symptoms, such as: nausea, vomiting, etc.; myelosuppressive reactions, such as: anemia, lowering of white blood cells and platelets, etc.; in addition, there are also symptoms such as allergic reactions and alopecia, etc. For these complications, we mostly adopt the principle of early detection and early treatment. Specific cases should be carried out under the guidance of specialists and standardized treatment in order to improve the efficacy and reduce adverse reactions.