Abstract: Objective To explore the effects of aerobic exercise combined with breathing training on cardiopulmonary function and quality of life in patients undergoing radiotherapy for chest tumors. Methods A total of 70 chest tumor patients who were scheduled for radiotherapy at Xuzhou Central Hospital from January 2024 to July 2024 were selected. They were randomly divided into two groups (n=35): a control group and an observation group. The control group received radiotherapy and routine nursing care, while the observation group underwent aerobic exercise combined with breathing training starting on the first day of radiotherapy, five times per week, for consecutive eight weeks. Both groups were compared for cardiopulmonary function cardiopulmonary exercise test (CPET) parameters: exercise time (T), peak oxygen uptake (VO_2peak), peak load power (WR_peak), carbon dioxide ventilation equivalent slope (VE/CO_2slope), peak heart rate (HR_peak), peak oxygen pulse (VO₂/HR_peak), peak metabolic equivalent (MET_peak), respiratory function forced vital capacity (FVC), forced expiratory volume in 1 second (FEV₁), FEV₁/FVC%, maximal voluntary ventilation (MVV), maximal inspiratory pressure (MIP), maximal expiratory pressure (MEP), and quality of life (QLQ-C30 scale) before and after the intervention. Results After intervention, the observation group showed increases in T, VO_2peak, WR_peak, VO₂/HR_peak, and MET_peak, and decreases in VE/CO_2slope compared with the control group. The observation group also presented higher FVC, FEV₁, FEV₁/FVC%, MVV, MIP, and MEP than the control group, and these measures were improved compared with those pre-intervention. Additionally, the observation group had better scores for physical function, emotional function, and overall health status, while the scores for fatigue, nausea and vomiting, pain, shortness of breath, insomnia, loss of appetite, and constipation were lower than those of the control group, and improved compared with those pre-intervention (P<0.05). After the intervention, the observation group showed higher VO_2peak, WR_peak, VO₂/HR_peak, and MET_peak, and lower VE/CO_2slope and HR_peak than those before intervention (P<0.05). In the control group, T, VO_2peak, WR_peak, and MET_peak were lower than those post-intervention, VE/CO_2slope was higher, and MVV, MIP, and MEP were lower than those before intervention. Additionally, the control group showed lower scores for physical function, emotional function, and overall health status, and higher scores for fatigue, shortness of breath, insomnia, and loss of appetite than those before intervention (P<0.05). Conclusions Aerobic exercise combined with breathing training can improve cardiopulmonary function and respiratory muscle strength in patients undergoing radiotherapy for chest tumor, enhancing their quality of life.