The book “Nei Wai Shang Bian Huo Luen” written by Dong-Yuan Li records the differences of diseases caused by internal and external factors as well as the treatment of diseases caused by internal factors. The 46 main prescriptions contained inside the book demonstrate Dong-Yuan Li’s style and reasoning when composing an herbal prescription. This article reviewed the main prescriptions of “Nei Wai Shang Bian Huo Luen” with “Tan Ye Ben Cao” written by Hao-Gu Wang, and statistically analyzed the formulas according to: frequency of use of the various herbs, grouping of herbs, up-lifting and down-bearing nature, channel entry and therapeutic mechanism. As a result, herbs are used in the main prescriptions for 398 times. The most frequently used herbs are Gan Cao (Glycyrrhiza glabra), Chen Pi (Citrus reticulata), Huang Qi (Atractylodes macrocephala) and Ren Shen (Panax ginseng). These herbs all belong to the “Dampness transforming” group which was also the most frequently showing pharmacological group of herbs with 147 occurrences. Most main prescriptions of the book are up-lifting in nature. The three most common channels used were the stomach channel (48.9%), spleen channel (22.5%) and lung channel (12%). The main therapeutic mechanism used is “Removal of lodged pathogenic influences”. So the most frequently showing pharmacological group of herbs is the “Dampness transforming” group. Most main prescriptions of the book are up-lifting in nature. “Nei Wai Shang Bian Huo Luen” was found to be mostly associated with the stomach (removal of food accumulation) and spleen (supplementing Qi) with the two channels associated to 70% of all prescriptions. Furthermore, the lung channel prescriptions were related to febrile diseases.