The main characteristic of normal skin is that it is affected by seasonal changes, being drier in winter and oilier in summer. Human skin is generally categorized into four types according to the secretion of its sebaceous glands: normal skin, dry skin, oily skin and combination skin. Neutral skin is healthy and ideal skin, sebum secretion is moderate, between dry and oily skin, not sensitive to external stimuli. Its pH value is 5.6 to 7. The main feature of normal skin is that it is susceptible to seasonal changes, as detailed below: 1. Winter is dry: winter windy weather becomes very much, the humidity in the air becomes smaller, will take away too much water in the skin, which will lead to skin dehydration and dryness. Winter can be used to moisturize the penetration of strong moisturizing cream to relieve dryness. 2. Summer is greasy: summer skin oil obvious, summer sweat more, the body metabolism faster, sebaceous glands greasy secretion exuberant, resulting in skin oil obvious. In summer, you can use some oil cleanser and oil control products to alleviate the grease. Neutral skin should pay attention to keep the skin clean and hygienic, if usually make-up, in the evening before going to bed need to remove make-up clean, eat more vitamin-rich foods, to ensure adequate sleep, go out and do a good job of sunscreen, anti-freezing, wind and sand, and so on.