Abstract:〔Abstract〕 Objective To analyze the effects of modified Wenxin Decoction on electrocardiogram and clinical indexes in patients with atrial fibrillation (AF). Methods Retrospective analysis was performed on AF patients admitted to Changde First Hospital of Traditional Chinese Medicine from January 2021 to December 2021. 46 patients receiving conventional treatment were included in the control group, and 46 patients receiving modified treatment with self-designed Wenxin decoction on the basis of conventional treatment were included in the observation group. The frequency and duration of AF attacks, the main and secondary syndroms of Traditional Chinese Medicine (TCM), tongue and pulse integrals, and the variation of ECG characteristics [P wave maximum time limit (Pmax), P wave minimum time limit (Pmin), P wave dispersion (Pd), P wave variation (Pv), R–R interval (R-R)] were compared between the two groups before and after treatment. Results After treatment, the attack frequency and duration of the two groups were lower than those before treatment, and after treatment, the attack frequency and duration of the observation group were lower than those of the control group, the differences were statistically significant (P < 0.05). After treatment, the scores of various TCM syndroms of the two groups were lower than those before treatment, and after treatment, the scores of various TCM syndroms of the observation group were lower than those of the control group, the differences were statistically significant (P < 0.05). After treatment, Pmax, Pd, and Pv in both groups decreased to varying degrees, with R-R higher than that before treatment. Moreover, after treatment, Pmax, Pd, and Pv in the observation group were lower than those in the control group, with R-R higher than that in the control group, the differences were statistically significant (P < 0.05). There were no serious adverse reactions affecting the treatment in both groups. Conclusion Self-designed Wenxin decoction can further reduce the frequency and duration of atrial fibrillation, alleviate various TCM syndromes of patients, improve electrocardiogram indexes, and the drug is safe and feasible.