Objective To investigate the predictive value of triiodothyronine and cognitive function in readmission of elderly patients with chronic heart failure (CHF) due to cardiovascular events. Methods Elderly CHF patients (≥65 years) admitted in the geriatric and cardiologic departments of Yichang Central People′s Hospital from September 2020 to September 2022 were enrolled. According to whether they were readmitted due to cardiovascular events within two years after discharge, they were divided into readmission group (n=79) and non-readmission group (n=54). General clinical data were compared between two groups. Multivariate logistic regression analysis was performed to identify risk factors in elderly CHF patients, and receiver operating characteristic (ROC) curve was plotted to evaluate the predictive value of each factor for the risk of readmissions due to cardiovascular events. SPSS statistics 26.0 and GraphPad Prism were adopted for statistical analysis. Data comparison between two groups was performed using student′s t test, χ² test or rank-sum test depending on data type. Results Significantly decreased albumin, blood calcium and triiodothyronine levels, larger ratio of co-existing diabetes, and declined cognitive function score were observed in the readmission group than the non-readmission group (P<0.05). Multivariate logistic regression analysis showed that triiodothyronine (OR=0.522,95%CI 0.303-0.900), blood calcium (OR=0.003,95%CI 0.000-0.777) and cognitive function (OR=71.093,95%CI 17.855-282.589) were independent risk factors for readmission in elderly CHF patients (P<0.05). ROC curve analysis indicated that the area under the curve of triiodothyronine and cognitive function in predicting the two-year readmission risk of cardiovascular events in elderly CHF patients was 0.660 (95%CI 0.561-0.758; P<0.01) and 0.913 (95%CI 0.866-0.960; P<0.001), respectively. Conclusion Triiodothyronine and cognitive function are independent risk factors in elderly patients with CHF, and have good predictive value for readmission risk of cardiovascular events.