Small-molecule phenolic substances widely exist in animals and plants, and have some sharedbiological activities. The metabolism of phenylalanine and tyrosine in the human body, and especially the metabolism of catecholamineneurotransmitters, produces endogenous small-molecule phenols. Endogenous small-molecule phenolic substances are functionally related to the important physiological processes and the occurrence of mental diseases in humans and some animals, which are systematically sorts and summarized in this review. Integrating the previous experimental research and literatureanalysis on natural small-molecule phenols by our research group, the understanding of the hypothesis that "small-molecule phenol are pharmacological signal carriers" was deepened. Based on above, the concept of "phenolomics" was further proposed, analyzed the research direction and research content which can bring into the knowledge framework of phenolomics. The induction of phenolomics will provide wider perspectives on explaining the pharmacological mechanism of drugs, discovering new drug targets, and finding biomarkers of mental diseases.