RESUMO
Colla Corii Asini(Ejiao)is an important Chinese medicine used in China for thousands of years, and is well known for its famous tonic properties. The herbalogical study was detailed carried out based on the naming, habitat, harvesting, processing, medicinal properties and clinical efficacy. The results showed that the name of Ejiao could be traced back to Shennong's Materia Medica, and various names of Lvpi Jiao, Penfu Jiao and Fuzhi Jiao were recorded in other ancient books. In the many intervening centuries, the main materials of Ejiao had been replaced from cow leather before Tang Dynasty to donkey skin in the middle to late Tang Dynasty. This phenomenon could be probably caused by complicated social factors of various periods and different efficacy of Ejiao made by all kinds of raw materials. Ejiao was merely processed with the simple methods before Tang Dynasty, which subsequently improved avariety of methods to enhance the supplementation action. Most importantly, Ejiao has a wide clinic application along with the development of processing theories and methods, which can be found in various Classics, especially in imperial medical case record in Qing Dynasty.