Objective: To analyze the characteristics and prognosis of heart rate variability in chronic heart failure patients with type 2 diabetes mellitus (T2DM). Methods: A total of 110 patients with chronic heart failure who were treated in Jiangyin Hospital of Traditional Chinese Medicine from July 2019 to June 2021 were selected as a research group. Sixty patients with pure heart failure were included in a study group A, and 50 patients with T2DM were included in a study group B. A total of 50 patients with structural heart disease without heart failure who were admitted to Jiangyin Hospital of Traditional Chinese Medicine during the same period were included in the control group. The differences in clinical data of the 3 groups were compared, and laboratory examinations, echocardiography, and 24-h dynamic electrocardiography were performed to analyze the differences in heart rate variability and prognosis among the 3 groups. Results: By univariate analysis, the course of disease, serum B-type natriuretic peptide (BNP), left ventricular end diastolic diameter (LVEDd), left ventricular ejection fraction (LVEF), cardiac output (CO), heart rate, the percentage of adjacent sinus R-R interval difference ≥50 ms in sinus rhythm (pNN50), the height ratio of the total number of sinus R-R intervals to the histogram of sinus R-R interval (TRI), the standard deviation of all sinus R-R intervals (SDNN), the root mean square (rMSSD) of the difference between adjacent sinus R-R intervals in the study group had significant different with the control group (all P<0.05); after multivariate analysis, the course of disease and BNP finally entered the regression equation (P<0.05). By univariate analysis, the course of disease, fasting blood glucose (FBG), BNP, mean heart rate, pNN50, TRI, SDNN and RMSD in the study group B were significantly lower than those in the study group A (all P<0.05); after multivariate analysis, FBG finally entered the regression equation (P<0.05). The levels of pNN50 and RMSSD in the study group B with course of T2DM ≥10 years were lower than those with course of T2DM <10 years (P<0.05). After 6 months of follow-up after discharge, the readmission rate in the study group B was higher than that in the study group A (P<0.05). Conclusion: Chronic heart failure patients with T2DM can further reduce heart rate variability, aggravate the degree of cardiac autonomic dysfunction, and affect their prognosis.