Oral lichen planus is a common chronic oral mucosal skin disease, unlike ringworm and tinea pedis, which are not caused by fungi and are generally not contagious. The pathogenesis of the disease is not yet fully understood, but current research suggests that its onset is related to mental factors (such as fatigue, anxiety, stress), immune factors, endocrine factors, infectious factors, microcirculatory disorders, micronutrient deficiencies, and certain systemic diseases (diabetes, infections, hypertension, gastrointestinal disorders). After certain drugs such as methyldopa, adiponectin, chloroquine, aminobenzol, Kepone, quinidine, etc., and certain herbal medicines, or when there are metal fillings or restorations in the oral cavity, changes similar to lichen planus may appear in the oral cavity or may aggravate the existing lichen planus lesions, which are significantly reduced or disappear after stopping the suspected drugs or replacing the fillings and restorations. Patients with oral lichen planus usually have no conscious symptoms, but some patients have roughness, woodiness, burning sensation of mucous membrane, and local sensitivity and burning pain when they encounter spicy, hot, sour or salty stimuli. The clinical manifestations of oral lichen planus are mainly white streaks, plaques, red congested lesions and vesicles in the oral mucosa (most common in the cheek, but also in the tongue, gums, lips and palate); the streaks and plaque lesions rarely have painful symptoms, while the congested and vesicular lesions mostly have painful symptoms. Patients with long-term untreated oral lichen planus may have Candida albicans infection in the oral cavity, so it is important to have regular examination of Candida in the oral cavity for timely treatment and relief of symptoms. In addition to the oral mucosa, some patients may also have lichen planus lesions on the genital mucosa, skin, and nails. The diagnosis of lichen planus is mostly based on clinical manifestations, but biopsy is required to confirm the diagnosis if necessary. The treatment measures of oral lichen planus should firstly change the bad habits of individuals, to live a regular life, to limit smoking, alcohol and stimulating diet such as chili, raw onion, raw garlic, etc., to pay attention to oral hygiene, to remove local irritants such as bad restorations, tartar, soft tartar and to keep the oral cavity clean. Drug treatment includes local drug treatment and systemic treatment. Local treatment is mainly for congested and eroded lesions with painful symptoms, and systemic treatment is mainly based on Chinese herbal medicine, which can dredge liver and Qi, activate blood circulation and remove blood stasis, and the condition of most patients can be effectively controlled, and a few western drugs are used for the treatment of lichen planus, including adrenocorticotropic hormones and immunomodulators, which are not widely used in clinical practice because of large side effects. It is difficult to eradicate lichen planus completely. The main purpose of treatment is to eliminate the damage of erosions in the mouth, relieve the symptoms of pain when eating, prevent further expansion of the lesions and stop malignant changes. Patients with lichen planus, especially those with vesicular lesions in the oral cavity, should have regular follow-up examinations so that the lesions can be noticed and controlled by doctors, and the medication regimen can be adjusted in a timely manner, and biopsies can be performed on areas with cancerous tendencies to take appropriate measures.