Theory of Chinese materia medica (CMM) nature was an important part in traditional Chinese medicine (TCM) theoretical system. During the long term practice, based on TCM theories of yin and yang, five elements, zang-fu, meridian and treatment principle, herbal features and patients' reactions were highly summarized into recognition and understanding. Since ancient time, theory of CMM nature has always guided the accurate syndrome differentiation and medication in TCM clinical practice. It contributed to the healthcare and reproduction of Chinese people. Theory of CMM nature is the basic theoretical knowledge which must be mastered in the study and research. Its concepts contained four-qi, five tastes, channel tropism, ascending and descending, toxicity, tonification and reducing, moisture and dryness, smooth and astringent, softness and hardness, fixed and itinerant effect, strong and mild. Using fixed and itinerant effects in the summarization of CMM function is one of the components in CMM nature theories. Although discussions on this theory from practitioners during past dynasties were in disorder, the significant guidance in herbal interaction mechanism and prescription compatibility should not be ignored.