Redness of the skin on the face may be related to skin allergy, rosacea, systemic lupus erythematosus, ringworm of the face and other diseases, and may also be related to physiological factors. 1. Skin allergy: when the skin is stimulated by some external factors, a metamorphic reaction may occur, which can be manifested in the clinic as redness, itchiness and rash. 2. Rosacea: also known as rosacea, is a group of skin diseases mainly characterized by facial erythema, maculopapular rash, and capillary dilatation, and the symptoms of skin redness will be significantly aggravated when exposed to sunlight or over-excited. 3. Systemic lupus erythematosus (SLE): is an autoimmune system abnormality disease, which is mainly manifested as butterfly-shaped erythema on the facial skin and prolonged low-grade fever in the clinic. 4. Ringworm of the face: it is a fungal infectious skin disease. It is a fungal infection of the skin. The skin of the face is red, well-demarcated erythema with itching. 5. Physiological factors: excessive mental tension, excitement, exercise and alcohol consumption may lead to dilation of blood vessels in the face, resulting in redness of the skin. For a long time the phenomenon of facial skin redness, there may be other reasons, it is recommended to go to the regular hospital dermatology consultation, clear diagnosis and symptomatic treatment.