Oral candidiasis is an acute, subacute and chronic fungal disease of the oral mucosa caused by Candida infection. With the extensive use of glucocorticoids, other immunosuppressants, antibiotics and other drugs. Oral candidiasis is becoming increasingly common in clinical practice. Candida itself is a conditionally pathogenic fungus. There are seven main species of Candida associated with human disease. Among them, Candida albicans and Candida tropicalis are the two most common Candida that can be isolated in the clinic. Candida albicans is the most pathogenic and most common of all seven species of Candida. Under normal circumstances, the pH of human mouth is neutral or weakly alkaline, while Candida is more likely to grow in an acidic environment. Patients with systemic diseases such as diabetes, anemia, hepatitis, AIDS and even long-term radiotherapy are particularly susceptible to Candida infection. Oral candidiasis is generally divided into four types: acute pseudomembranous candidiasis, acute atrophic (erythematous) candidiasis, chronic atrophic (erythematous) candidiasis and chronic proliferative candidiasis. Acute pseudomembranous candidiasis, commonly known as “thrush”, mainly occurs in newborns, infants, or patients who use antibiotics or hormones for a long time. The main manifestation is congestion of the oral mucosa, with a white milky or yellowish pseudomembrane visible on the surface, which can be wiped away with a little pressure, and a congested mucosal base can be seen below the lesion. The infection can even spread to the back of the mouth to the oropharynx, trachea and esophagus, causing candidiasis of the digestive and respiratory tracts. Acute atrophic (erythematous) candidiasis, commonly known as antibiotic stomatitis, can develop alone or in conjunction with pseudomembranous candidiasis. These patients usually have a long history of high doses of antibiotics or hormones. The lesions tend to develop on the tongue, with atrophy of the lingual papillae at the midline of the dorsal tongue and, in severe cases, the formation of small ulcerated surfaces and corresponding erythematous areas of congestion on the palatal mucosa. Chronic atrophic (erythematous) candidiasis, also known as denture stomatitis, is the most common type in elderly patients. The course of the disease can last for months or even years and can recur. The most common manifestation is redness and swelling of the mucosa in the denture-bearing area. There may be symptoms of dry mouth and burning sensation. The lingual papillae are atrophic and the dorsum of the tongue is red with corners of the mouth erosion. Candida pseudofilaments and spores can usually be examined on the denture abutment surface. Chronic proliferative candidiasis, mainly seen in patients who smoke or have poor oral hygiene, tends to occur in the joint area of the corners of the mouth, with mucosal congestion and erosion and the appearance of nodules or granules. There is also a relatively rare type of chronic mucocutaneous candidiasis that may be hereditary with familial attacks. The manifestation in the oral cavity is mainly chronic atrophic candidiasis. For oral candidiasis, it is necessary to exclude the causative factors and keep the oral cavity clean and hygienic. Rational use of antibiotics and glucocorticoids is recommended to prevent and control dysbiosis. If antibiotics are really needed for a long time due to systemic diseases, they can be replaced by drugs with different antibacterial spectrum in about two weeks, while paying attention to maintaining oral hygiene conditions. The common clinical treatment is to rinse or scrub the mouth with alkaline sodium bicarbonate solution, oral mycophenolate tablets or oral fluconazole, itraconazole and other antifungal drugs. If the mouth wears movable dentures for a long time, the treatment must also clean the dentures at the same time. Remove the dentures before going to bed and soak them in an alkaline solution of sodium bicarbonate. If necessary, a new removable denture will need to be made. If there are hyperplastic lesions in the oral cavity, they need to be closely monitored and, if necessary, removed for biopsy to prevent cancer.