The present disclosure discloses a dye for industrialization of dyeing cotton fiber in supercritical carbon dioxide that can react with cotton fiber, wherein a preparation method therefor comprises the following steps: dissolving a hydroxyl-containing natural dye in an organic solvent, dropwise adding an alcohol compound containing a halogen group into a reaction system in the presence of an acid-binding agent, precipitating the product with another solvent after the reaction is completed, and then filtrating and drying to obtain the compound described. The obtained compound is used for dyeing cotton fiber in supercritical carbon dioxide. The dye provided by the present disclosure is capable of dyeing cotton fiber in supercritical carbon dioxide conditions, and has a better color fastness while dyeing the cotton fiber.