The use of traditional medicines including natural drugs, especially traditional Chinese medicine (TCM), plays an important role in the prevention and treatment of human diseases; however, so far, the mechanism of its prevention, health care and treatment of diseases is unclear. Here, I propose that the core mechanism of traditional medicines is to correct the relative deficiency of potassium ions in body and at the same time improve the utilization efficiency of potassium ions, so as to improve or restore cell functions in organs and tissues, and let the body return to a normal state. In order to achieve such a core goal, the therapeutic effect of natural drugs has an important relationship with the rational matching of prescriptions and the quality of drugs, with particular emphasis on the concentrations and quantum energy levels of potassium ions or their compounds in the formula. The understanding of the core effect of potassium in natural drugs has a specific and important guiding role for the artificial cultivation and rational use of natural drugs. Moreover, these ideas may also provide an important theoretical basis for the development of modern agriculture and medicine, and the rational and comprehensive utilization of potassium resources.