Dermatophytosis is a superficial infection of the hair, skin and nails caused by dermatophytes, but there are also reports of deep infections. Common clinical cases are tinea capitis, tinea corporis, tinea cruris, tinea manuum, tinea pedis and tinea pedis. Occasionally, deep tissues may be involved. Deep infection may occur. Dermatophytes and their metabolites may cause allergic reactions of the skin outside the lesion through blood circulation, which is called dermatophytids. Dermatophytosis is a group of common and frequently occurring diseases. Among the cases of dermatological visits, it is second only to dermatitis and eczema, and ranks first among infectious skin diseases. In my country, the number of patients is at least in the hundreds of millions, so actively preventing and treating dermatophytosis has important clinical and social significance.