Zhang Yuan-Su(張元素) was a doctor of the Jin(金) period, who was followed by Li Dong-Yuan(李東垣) and Wang Hao-Gu(王好古), creating the Yishui School(易水學派). The most notable aspect of his theory is the internal organs(臟腑)-based diagnostic system. He organized previous methods based on the internal organs and applied the same methodology in treatment as well. The Zangfu-biaoben-xushi-hanre-yongyaoshi(臟腑標本虛實寒熱用藥式) is one of his major publications in which diagnostic and treatment methods are organized in a simple manner. In this book, the diseases of the organs are divided into the tip and root(標本). This paper investigates the standards of categorizing tip and root diseases through analysis of all symptoms of both tip and root diseases of the five internal organs. Then the results of the analysis were used in grasping the similarities and tendencies of the root disease and tip disease. Conclusively, root diseases indicate disorder in the internal organs themselves. Tip diseases indicate disorder in the channels and collaterals, diseases caused by exterior pathogens or symptoms that manifest in the exteriors of the body. Such categorization is thought to have been established to eliminate diagnostic error that could occur from using the same expressive means in describing symptoms with different causes, in the process of forming an uncomplicated diagnostic system.