Abstract: Cassia twig, derived from the dried tender twigs of Cinnamomum cassia, is a traditional Chinese medicine with a long application history and extensive clinical utility, which is widely distributed in China and Southeast Asia. Its main active components, such as cinnamaldehyde and cinnamic acid, have been confirmed by modern pharmacological studies to exhibit multiple biological activities, including anti-inflammatory, antimicrobial, antioxidant, antitumor, and immunomodulatory effects. In clinical practice of traditional Chinese medicine, cassia twig is widely used for the treatment of colds, joint pain, and menstrual disorders and other diseases. However, excessive use or improper administration may induce toxic reactions. This article reviews the chemical components, pharmacological properties and medicinal value of cassia twig, aiming to provide a reference for the in-depth study on its action mechanisms and medication safety, as well as for its rational clinical application and innovative drug development.