Natural products have attracted wide attention in the cosmetics market due to their safety and high efficiency. As a highly active substance in nature, natural polysaccharides have been reported in recent years to have various cosmetic activities such as moisturizing, whitening, anti-aging and repairing skin, and are becoming a hot research topic in cosmetics industry. At present, the mechanism of polysaccharide exerting cosmetic activity has been widely studied, but the relationship between polysaccharide's chemical structure and cosmetic activity has not been effectively analyzed, which leads to the limitation of polysaccharide development. In this review, the mechanism of polysaccharides exerting cosmetic activities such as moisturizing, whitening, anti-aging and skin repair was introduced. The potential relationship between the structure and activity of polysaccharides was summarized by analyzing the influence of physical and chemical properties of polysaccharides, such as extraction method, molecular weight, monosaccharide composition, functional group and structural modification, etc., which laid a foundation for the analysis of the structure activity relationship of polysaccharides and improved its cosmetic value.