Xenohormesis explains how bioactive secondary metabolites produced by environmentally stressed plants can confer stress resistance and survival benefits to animals that consume them. This principle holds that animals retain the ability to sense these stress-induced signaling molecules under nature selective pressure, which will activate the evolutionarily conserved cellular stress response and subsequently enhance their adaptation to adversity. In this review, we have introduced the concept and mechanisms of xenohormesis, analyzed and summarized the xenohormesis relationship between plants and insects or human beings. Based on these, we have elucidated the traditional Chinese medicine (TCM) xenohormesis with ginseng as an example, proposed that we could understand the essence of TCM biological effects from an evolutionary and ecological perspective with the help of xenohormesis principle and also pointed out it has very important value in the modernization of TCM.