Alkali cellulose is a natural macromolecule. Each fiber-based ring contains three hydroxyl groups. The most active hydroxyl groups react to form hydroxyethyl cellulose. Soak raw cotton linters or refined pulp in 30% liquid caustic soda, take out and press after half an hour. Squeeze until the ratio of alkaline water reaches 1:2.8, and then pulverize. The crushed alkali cellulose is put into the reaction kettle, sealed, vacuumed, filled with nitrogen, and the air in the kettle is completely replaced by repeated vacuuming and nitrogen filling. Press into the pre-cooled ethylene oxide liquid, pass cooling water into the jacket of the reactor, and control the reaction at about 25°C for 2 hours to obtain crude hydroxyethyl cellulose. The crude product was washed with alcohol, neutralized with acetic acid to pH 4-6, and then cross-linked with glyoxal for aging. Then it is washed with water, centrifuged, dried, and ground to obtain hydroxyethyl cellulose.