Cinnamon Twig Decoction Plus Dragon Bone and Oyster Shell， originated from “Treatise on Febrile and Miscellaneous Diseases”， is often used in treating seminal emission. But Zhang’s records only list symptoms but without pathogenesis. However， the decoction also has good effect on palpitations in clinical practice. Thus， it is necessary to explore the mechanism. This article explained the etiology and pathogenesis of heart palpitations from three aspects， namely nutrient-qi and defense-qi， heart spirit and heart-kidney. Moreover， the therapeutic mechanism of this formula was discussed， and also a medical record so as to provide guidance and references for clinical application.