〔Abstract〕 Objective To analyze the correlation between plasma midregional pro-atrial natriuretic peptide (MR-proANP) and cardiopulmonary exercise test (CPET) parameters in elderly patients with heart failure. Methods The medical records of 110 elderly patients with heart failure who were treated in the Fifth Affiliated Hospital of Zhengzhou University from July 2020 to July 2021 were retrospectively analyzed. According to the heart function grading results of New York Heart association (NYHA), the patients were divided into three groups: 40 patients with heart function grade Ⅱ group; 40 patients with heart function grade Ⅲ group; 30 patients with heart function grade Ⅳ group. Serum MR-proANP level and CPET were detected in the three groups. Peak oxygen uptake (PeakVO2), equivalent slope of carbon dioxide ventilation (VE/VCO2 slope), peak oxygen pulse (VO2/HR), slope of oxygen uptake to power ratio (VO2/WR slope), anaerobic valve (AT) and serum MR-proANP levels of patients in the three groups were compared. The correlation between serum MR-proANP and CPET parameters was analyzed. Results Compared with heart function grade Ⅱ group, PeakVO2, VO2/HR, VO2/WR slope and AT levels were lower than those in heart function grade Ⅲ group and heart function grade Ⅳ group, while VE/VCO2 slope level was higher, the differences were statistically significant (P < 0.05). Compared with heart function grade Ⅲ group, PeakVO2, VO2/HR, VO2/WR slope and AT levels in heart function grade Ⅳ group were lower, and VE/VCO2 slope was higher, the differences were statistically significant (P < 0.05). MR-proANP levels were higher in grade Ⅲ and grade Ⅳ groups than those in grade Ⅱ group, and the differences were statistically significant (P < 0.05). Compared with grade Ⅲ group, the level of MR-proANP in grade Ⅳ group was higher, and the difference was statistically significant (P < 0.05). Spearman correlation analysis showed that PeakVO2, VO2/HR, VO2/WR slope and AT were negatively correlated with MR-proANP (P < 0.05), while VE/VCO2 slope was positively correlated with MR-proANP (P < 0.05). The correlation between VE/VCO2 slope and MR-proANP was the highest (R = 0.638, P < 0.05). Conclusion There was a negative correlation between serum MR-proANP and the levels of PeakVO2, VO2/HR, VO2/WR slope, AT in elderly patients with heart failure. And there was a positive correlation between serum MR-proANP and the level of VE/VCO2 slope in elderly patients with heart failure.