The present invention discloses a novel usage of catalpol. The novel usage refers to the application of catalpol in the preparation of a drug or health food for treatment of hyperthyroidism, and to the application of catalpol in the preparation of a drug or health food for treatment of hyperthyroidism related cardiopathy. Experiment results show that catalpol is capable of improving behaviors of the hyperthyroidism mice； has the potential of increasing the body weight of the mice； decreases oxygen consumption and heart rate； has prominent effects on reducing T 3 , FT 3 and FT 4 ； has prominent effects on reducing heart weight index and left ventricular weight index.
