Oral lichen planus is a relatively common oral mucosal disease, which can have a systemic disease or be a symptom of a systemic disease in the oral cavity, or can occur in the oral mucosa alone. The most basic pathological manifestation is atrophy or thickening of the mucosal epithelium, and the atrophic area of the mucosal epithelium is clinically red, while the hyperplastic area is clinically white. The red-white reticular structure of flat moss exhibited by atrophy and atrophy is shown as cell atrophy and hyperplasia on pathological section. In addition to epithelial thickening and thinning, pathological changes of lichen planus can be seen, mainly intercellular bridges between epithelial cells are broken, when epithelial basal cells change to a certain extent, vacuolated basal cell changes and liquefied degeneration of basal cells can be seen, as well as the formation of subepithelial blisters and the structure of inflammatory lymphocytic infiltration zone in the lamina propria.