Hematoxylin (Hematoxylin) and Eosin (Eosin) co-staining referred to as HE staining is one of the most commonly used staining methods in pathology and histology. Hematoxylin is an alkaline natural dye that can color the cell nucleus. The main component of chromatin in the cell nucleus is DNA, and in the double helix structure of DNA, the phosphate groups on the two nucleotide chains are outwardly oriented, which makes the outside of the double helix of DNA negatively charged and acidic, and it can easily be stained by combining with the positively charged Hematoxylin alkaline dye by ionic bonding or hydrogen bonding. The methods of hematoxylin maturation are natural oxidation and chemical oxidation; natural oxidation means exposure to light and air, the process is slow, ranging from about 3 to 6 months, but the staining ability of the product can be maintained for a very long time, Ehrlich and Delafield hematoxylin belongs to this kind; Ehrlich hematoxylin, as a good nuclear staining solution, is also used in the staining of mucin such as mucopolysaccharides of cartilage, and Ehrlich Hematoxylin stain is also recommended for staining bone and cartilage.