This study aims to analyse the clinical efficacies of electrocardiogram (ECG) in diagnosing cardiac autonomic dysfunction (CAD) and to explore the clinical values of this method. A total of 82 CAD patients clinically diagnosed and confirmed were selected for the traditional Chinese medical treatment and psychological intervention. After three courses of treatment, their ECG were monitored, and the diagnostic results before and after the treatment were then compared. Before the treatment, the abnormality rate of the patients ECG diagnosis was 100%; while after the treatment, the rate was reduced to 10.98% (9/82). The intragroup comparison showed that the post-treatment abnormal ECG rate was significantly reduced and exhibited statistically significant difference with that before the treatment (P<0.05). Meanwhile, after the treatment, such clinical symptoms as palpitation, shortness of breath, or precordialgia were significantly improved, and the symptoms in 73 patients totally disappeared. The application of ECG in the clinical diagnosis of CAD was non-invasive and simple, and had high detection rate and accuracy; therefore, it had high clinical values and was suitable for wide promotion.