The structure of sanitary napkins can be divided into surface layer, inner layer, side and back glue.

The surface layer is the part that is in direct contact with the skin, and its material must be soft. The weave and indentations on the surface determine the effect of absorbing menstrual blood and preventing it from seeping back. PE surface layer and cotton surface layer are the two most commonly used materials. The PE surface layer with microporous design can prevent menstrual blood from seeping back easily and make users feel dry. However, the material is hard and may cause allergic reactions in some users; Due to the improved absorbency design of cotton, the market share after 2001 has gradually become higher than that of organic soft skin soft nonwoven sanitary napkins with PE surface.

The inner layer is mainly made of cotton, non-woven fabric, paper pulp or polymer and polymer composite paper formed by composites of the above materials, which are used to absorb the menstrual blood flowing out. The side design is mainly used to prevent side leakage, because when used, it will be at an angle with the sanitary napkin body, making it easier for friction with the groin area. Therefore, sanitary napkins with soft material side edges are more popular among women. The adhesive backing of sanitary napkins is an impermeable material that can retain menstrual blood in the sanitary napkin. Adhesive sanitary napkins were developed in the 1970s. Super thin sanitary napkins facilitate fixing the sanitary napkin to the inside of underwear and reduce sanitary napkins. The towel is displaced.

The principle that SAP sanitary napkins can quickly absorb water (blood) is that it contains a polymer absorbent material in the middle. The component is sodium polyacrylate. Before absorbing water, it is a small particle similar to powder. After absorbing water, it will expand and lock the moisture in it.