In tumors, herbal medicine can regulate the expression of tumor-related genes by influencing the methylation and acetylation of histones at the gene promoter or enhancer by controlling the expression of CBP, SUV39H1, EZH2, JMJD3, UTX, NSD1, etc. At the same time, herbal medicine can also regulate the methylation of DNA by affecting the expression of TET3, UHRF1, DNMTs, etc. In epigenetic studies of other diseases, herbal medicine shows the great potential of clinical applications in treating amnesia, allergic asthma, diabetes, inflammation, and liver fibrosis. The gene discussed is EZH2; the disease is diabetes mellitus.