Abstract: microRNA (miRNA) is a class of endogenous~21nt non-coding single-strand small RNAs which play important roles in plant growth and development, signal transduction, stress response, and secondary metabolism. In recent years, a large number of miRNAs have been identified in various medicinal plants, and the regulatory effects of these miRNAs have been preliminarily studied. In medicinal plants, most of the active components are secondary metabolites, so it is of great significance to study the regulatory effects of miRNA on the formation of secondary metabolites. In this paper, the general research methods of plant miRNA and the research progress of medicinal plant miRNA and their regulatory effects on the formation of bioactive metabolites were reviewed, and the future direction of medicinal plant miRNA was prospected, so as to provide reference for the future research of medicinal plants.