Fungal disease is a disease caused by fungi fungi are eukaryotic organisms, with nucleus and organelles, no chlorophyll, to absorb as a form of nutrition, sexual and asexual reproduction, the basic form of mycelium and (or) spores. Fungi like warm and humid, the optimal growth temperature 22 ℃ ~ 36 ℃, relative humidity 95% ~ 100%, the optimal pH 5.0 ~ 6.5. fungal cell wall contains chitin and (or) cellulose, strong resistance to external environmental changes. Ultraviolet light and X-rays can not kill fungi, but at about 100 ℃ most fungi can die in a relatively short time, so boiling disinfection is both economic and convenient and efficient. Fungi are found all over the natural world, and among the 50,000 to 250,000 species of fungi that have been recorded, less than 200 are related to human diseases. With few exceptions, the source of fungal infections in humans comes from the external environment, obtained by aspiration, ingestion or traumatic implantation. A few fungi can cause disease in normal people most of them only under special conditions and mostly invade weakened hosts. With the development of modern medicine, the use of broad-spectrum antibiotics, glucocorticoids, immunosuppressants, antitumor drugs, etc., organ transplantation, burn resuscitation, various catheter and intubation techniques, the application of intravenous high nutrition, etc., although prolonging the life of the patient, but long-term illness makes the body resistance to decline, the infection of conditionally pathogenic fungi increased significantly. It is now believed that any fungus that can survive at host body temperature (37°C) and low redox state (a state of damaged tissues) is a potential pathogenic fungus for humans. Fungi are generally classified as dermatophytes, yeasts, and molds. Fungal diseases are generally classified clinically into two categories: superficial and deep fungal diseases. Dermatophytes mainly include Trichophyton spp., Microsporum spp. and S. epidermidis. The common feature is pro-keratin, which can invade the cuticle, hair, and nail plate of human or animal skin, causing superficial fungal disease called dermatophytosis, or ringworm for short, and occasionally causing subcutaneous tissue infection. Superficial fungal diseases are basically named according to various parts of the body, such as ringworm of the head, ringworm of the body, ringworm of the femur, ringworm of the hands, ringworm of the feet, etc. However, a few are named according to the species of fungi, such as ringworm fungus causing ringworm fungus; ringworm fungus causing ringworm fungus. Yeast is a unicellular fungus that is mainly budding, and mycobacteria are characterized by growing hair-like mycelium under culture conditions, mainly invading hosts with severely depressed immunity, such as SLE, AIDS, etc., causing deep fungal disease Deep fungal disease includes subcutaneous tissue infection and systemic infection. Generally named according to the strain, subcutaneous tissue infections such as sporulating filamentous fungi cause sporotrichosis; systemic infections such as Candida caused by Candida (some cause superficial fungal disease), Cryptococcus neoformans cause cryptococcosis, etc. The diagnosis of fungal disease mainly relies on clinical manifestations and mycological examination, of which direct microscopic examination and culture of fungi has a decisive value, especially the scales and secretions of potassium hydroxide smear microscopic examination method is simple, rapid and easy to master. However, microscopic examination can only determine the presence or absence of mycelium and spores, can not identify the species, positive indicates the presence of fungi, once negative can not be completely negative. Identification of strains need to do culture. Commonly used medium for sand castle medium, culture positive can be transferred to a special medium, according to morphological, biochemical and other characteristics of the strain identification. Take lesion tissue for pathological examination, by special staining (PAS or hexamine silver staining) can find the fungus in the tissue and the pathological changes caused by it, which is meaningful for the diagnosis of deep fungal disease.