Eczema is a common inflammatory skin disease caused by a variety of internal and external factors, diagnosed on the basis of no characteristic examination indicators, relying mainly on clinical manifestations and physical examination. The rash is polymorphic, with symmetrical attacks and a chronic course. Eczema is divided into acute, subacute and chronic phases. Acute eczema is characterized by erythema and red papules of varying sizes, accompanied by itching, scratching, flowing water, erosion and exudation. With the prolongation of the disease, exudation decreases and transitions to subacute eczema. With the change of time, the local rash thickens and gradually evolves into chronic eczema. Based on these typical signs, eczema can be diagnosed. Since eczema is a metabolic disease, external environmental factors have a certain degree of influence on eczema, you can look for the cause in this regard, you can go to the hospital for allergen screening, screening for food and inhalant allergens in daily life. Eczema on the hands and feet should be differentiated from fungal infections, and you can take skin scraps for a fungal examination to rule out tinea capitis. Eczema in some special areas, such as scrotal eczema and eczema in the breast area of women, need to be alerted to eczema-like carcinoma if they have long-term episodes and cannot heal, in which case tissue needs to be taken for pathological examination. In conclusion, eczema needs to be considered when polymorphic rashes such as erythema, papules, vesicles and oozing appear on the skin, and depending on the situation, allergen examination, fungal examination and histopathological examination can also be done to aid in the diagnosis.