Background: To explore the therapeutic effect of Tongxinluo capsule (Tongxinluo) on patients with Syndrome X and Affective Disorder. Methods: Fifty-six patients with Syndrome X and Affective Disorder were randomly divided into a Tongxinluo capsule group and a placebo control group. The duration of treatment was 12 weeks. A 6-minute walking test, exercise load electrocardiogram and clinical symptom assessment were performed before and after treatment. After 12 weeks of treatment, the scores of the Self-Rating Anxiety Scale (SAS) and Self-Rating Depression Scale (SDS) were repeated. The levels of serum endothelin-1 (ET-1) and nitric oxide (NO) were measured before and after treatment. Results: Compared with the placebo control group, the Tongxinluo group SAS and SDS scores were lower than those before treatment (all P < 0.01), and the 6-minute walking distance increased significantly (P < 0.01). Clinical symptoms were significantly improved. The exercise test results suggested that, while improved, there was no significant difference (P > 0.05) when compared to before treatment. In the Tongxinluo treatment group, the levels of plasma endothelin-1 decreased significantly (P < 0.01) and nitric oxide levels were significantly increased (P < 0.01), with a significant difference when compared to the control group (P Conclusions: The Tongxinluo capsule can improve the Affective Disorder of Syndrome X, reduce the degree of anxiety and depression, increase exercise tolerance, reduce clinical symptoms, and improve vascular endothelial function.