Skin wrinkles are the obvious signs and manifestations of skin aging: they are the result of the combined effect of endogenous and exogenous factors. Those caused by irresistible factors (such as gravity, endocrine and immune function changes) and endogenous factors such as heredity are natural aging, manifesting as fine wrinkles and sagging skin. Those caused by environmental factors such as sunlight, smoking and occupational harmful chemicals are exogenous aging, among which ultraviolet radiation in sunlight is the most important factor affecting skin aging in the environment, also known as photoaging, which manifests as dry skin, loss of elasticity, thick and deep wrinkles, leather-like appearance, etc. Causes of skin aging: The decrease of skin tissue water and the morphological and biochemical changes of collagen fibers, elastic fibers and matrix (mucopolysaccharide) in the dermis and the atrophy of subcutaneous adipose tissue are the structural basis for the formation of wrinkles in the skin aging process. The intrinsic and extrinsic factors that can cause this change in the basic dermal structure are the key factors that lead to skin aging and wrinkles. As the skin ages, the epidermis and the dermis become flat, the epidermis becomes shallow, the epidermis area is relatively larger than the dermis area, making the skin lines deepen and water loss and increase; the natural moisturizing factor in the epidermal stratum corneum keeps decreasing, the hydration capacity of the skin keeps decreasing, and the water in the skin tissue cells decreases; the small sweat glands and sebaceous glands of the skin atrophy, the secretion capacity weakens, the water-lipid emulsification on the skin surface The small sweat glands and sebaceous glands of the skin atrophy, the secretion capacity decreases, the water-lipid emulsion on the skin surface decreases, the hydration capacity of the skin decreases, the water of the skin tissue cells decreases, the cells wrinkle, aging, and fine wrinkles appear. Proteoglycans and hyaluronic acid are connective tissue macromolecules that have special water storage and moisturizing abilities and play an important role in ensuring moisture in the dermis. As we age, the concentration of proteoglycans and hyaluronic acid decreases and the dermis becomes less hydrated, resulting in dryness, atrophy and wrinkles. On the one hand, as we age, dermal fibroblasts gradually shrink and become inactive, and the ability to synthesize collagen fibers decreases; at the same time, most of the cross-links between collagen molecules become non-reductive, collagen solubility decreases, and its stability increases with aging, resulting in reduced collagen water storage, dry skin, and reduced elasticity. At the same time, elastin synthesis is also significantly reduced, coupled with the degradation of elastic fiber decomposition, resulting in a decrease in the number of elastic fibers. On the other hand, UVA and UVB irradiation in sunlight can produce highly reactive free radicals, which, through oxidation and cross-linking, can damage DNA and react with proteins, lipids and coenzymes, causing damage to cell membranes and some cellular enzymes, such as superoxide dismutase, catalase, glutathione peroxidase, etc., resulting in various kinds of damage in the skin. The damage of various cells in the skin and the infiltration of inflammatory cells in the upper dermis. Inflammatory cells in the upper dermis can secrete elastase and collagenase, while damaged epidermal cells can release cytokines and metabolites of arachidonic acid, which promote the degradation of collagen and degeneration of elastic fibers in the dermis. In the dermal reticular layer, collagen fiber bundles are wavy in distribution, and their elasticity depends entirely on the action of elastic fibers. When the elastic fibers degenerate and lose their function, the collagen fiber bundles become irrational retraction and straighten, which leads to skin laxity and wrinkles. As we age, the capacity of subcutaneous fat cells decreases and the adipose tissue gradually shrinks, resulting in the loss of support for the lower dermal reticular layer and the fibrous trabeculae of the fascia, causing skin relaxation, which, together with the effect of gravity, causes the sagging of the relaxed skin and the formation of creases. In addition, facial wrinkles are also related to facial expression muscles, which are attached to the skin, and when it contracts the skin can appear wrinkles at right angles to its contraction, and increase and deepen with the increase of years.