Objective To explore the prognostic value of fragmented QRS, heart rate variability and heart rate deceleration force in patients with old myocardial infarction. Methods 115 patients with old myocardial infarction analyzed retrospectively were treated in The Second Affiliated Hospital of Liaoning University of Traditional Chinese Medicine from March 2019 to August 2020. According to the prognosis, they were divided into two groups: 72 patients with good prognosis(no adverse cardiovascular events) and 43 patients with poor prognosis(adverse cardiovascular events).The heart rate deceleration force, heart rate variability and fragmented QRS wave of the two groups were compared,ROC curve was used to analyze the efficacy of the above indexes in predicting the prognosis of patients.According to the death of the prognosis group, the patients were divided into two groups: the death group(10 cases) and the non death group(33 cases). After comparing the heart rate deceleration force, heart rate variability and fragmented QRS wave of the two groups. The above indexes were analyzed by ROC curve to predict the death of patients. Results The interval difference of DC, DR8(DC occurring continuously in 8 cardiac cycles), DR4(DC occurring continuously in 4 cardiac cycles), DR2(DC occurring continuously in 2 cardiac cycles) and adjacent normal R-R was＞50 in the good prognosis group The percentage of MS(pNN50), root mean square difference of adjacent normal R-R interphase(rMSSD), standard deviation of 24 h consecutive 5 min normal R-R interphase(SDANN index), standard deviation of 24 h normal R-R interphase(SDNN) were higher than those of poor prognosis group(P＜0.05). The positive rate of fragmental QRS was lower than that of THE group with poor prognosis(P＜0.05). DC, DR8, DR4, DR2, pNN50, rMSSD, SDANN index and SDNN were higher than those in the non-fatal group(P＜0.05). Spearman analysis showed that the prognosis and mortality of patients were positively correlated with pNN50, rMSSD, SDANN index, DR8, DR4, DR2, SDNN and DC. The prognosis was also positively correlated with the positive rate of fragmented QRS. After ROC curve analysis, Early prognosis AUC of DC, DR2, pNN50, rMSSD, SDANN index, SDNN, DR8, DR4 and fragmented QRS positive rate were 0.995, 0.999, 0.951, 0.998, 0.910, 0.816, 0.903, 0.917 and 0.747, respectively. The AUC for predicting death was 0.97, 0.939, 0.806, 0.994, 0.991, 0.948, 0.871, 0.900 and 0.647, respectively. Conclusion Heart rate deceleration force, heart rate variability, and fragmented QRS complex have good reference value in evaluating the prognosis of old myocardial infarction.