Objective: This study mainly focuses on the impact of different intensities of cardiac exercise rehabilitation on the prognosis of patients with chronic heart failure. Method: This study selected 108 patients with chronic heart failure admitted to the hospital between April 2022 and November 2022 as the subjects of this study. The patients were divided into high-intensity interval exercise group HIIT (37 cases), moderate-intensity continuous exercise group MICT (36 cases), and control group 35 cases. Among them, the high-intensity interval exercise group and moderate-intensity continuous exercise group received 6 months and 12 months of exercise rehabilitation intervention, respectively, while the control group did not receive any exercise rehabilitation intervention measures. Then, compare the changes in ejection fraction, six-minute walking distance, NT-proBNP, and other aspects among the three groups of patients. Result: Through research, it was found that the LVEF values of the high-intensity interval exercise group and the moderate-intensity continuous exercise group were higher than those of the control group. The six-minute walking distance of the high-intensity interval exercise group and the moderate-intensity continuous exercise group was higher than that of the control group. The values of NT-proBNP in the high-intensity interval exercise group and the moderate-intensity continuous exercise group were lower than those in the control group. The above research results indicate that the difference is statistically significant, P < 0.05. Conclusion: According to the research results, different intensities of cardiac exercise rehabilitation have a significant impact on the prognosis of patients with chronic heart failure. It can not only improve the LVEF and prolong the six-minute walking distance of patients, but also effectively reduce NT-proBNP. Therefore, it is worthy of clinical application and promotion.