Gas phase method: The gas phase method is to add additives or diluents during the reaction process, and the alkali fibers and EO react in the gas phase. The cotton fibers were soaked and activated in 18.5% NaOH solution, then pressed and crushed and placed in the reactor. The reactor was evacuated, filled with nitrogen twice, EO was added, and the reaction was obtained at a vacuum degree of 90.64kPa and 27-32°C for 3-3.5 hours.

Liquid phase method: The liquid phase method is to carry out the etherification reaction in the presence of a diluent. After alkalization and pressing, the cotton linters are reacted with EO at 20-60° C. for 1-3 hours in the presence of a diluent to obtain crude hydroxyethyl cellulose. Common diluents are acetone, isopropanol, tert-butanol or their mixtures. The product remains insoluble in the diluent.