Feeling stiffness in the chest after postoperative chemotherapy for thymic tumors may be the result of nerve and soft tissue damage, or may be considered a complication. Thymic tumors are a group of neoplastic diseases originating from the epithelial cells of the thymus, the etiology of which has not yet been clarified and may be due to genetic inheritance, alcohol, tobacco, ionizing radiation and other factors. If a patient develops chest stiffness after surgery and chemotherapy, it is mostly considered to be caused by damage to muscles and soft tissues due to chemotherapy. If patients after postoperative chemotherapy for thymus tumor suffer from some kind of stimulation of thymus gland, which leads to the sudden appearance of complications of myasthenia gravis, the patients show that the muscles gradually lose their strength, and the patients may feel fatigue and have the symptom of stiffness of chest, which can be aggravated by exercise, and may be accompanied by difficulty in swallowing, difficulty in breathing, and so on. If chest paralysis occurs after postoperative chemotherapy for thymus tumor, patients should go to regular hospitals and undergo relevant examinations so as to clarify the cause of the disease. Once diagnosed, they should actively cooperate with doctors to take relevant treatment measures.