Flax samples (hackled and flock) were analyzed for chemical content in gray and after different steps of preparing processes. The role of every stage in the total process of production flax cellulose by peroxide-alkaline, chlorite-peroxide-alkaline, and chlorite-alkaline methods was determined. The effects of these methods on the degree of cleaning of flax from noncellulosic compounds, whiteness, and degree of polymerization of flax cellulose were compared. The highest cleaning effect was found for the chlorite-peroxide-alkaline and chlorite-alkaline methods and the highest degree of cellulose polymerization was for the chlorite-alkaline one.