Foulier transferred infrared(FTIR) method was applied to analyze the differential chemical composition at different layers of wheat straw,and find out the influence of hot-water treatment.It was found that:Wheat straw is covered with inorganic substances,e.g.,silicon dioxide,and with few hydroxyls at outside surface,but contains abundant hydroxyls inside in cellulose,hemi-cellulose,and lignin.Through hot-water treatment,part of the simple hydrocarbons can be sovled with treating time as a significant factor;With low-concentration sodium hydroxide solution,even silicon dioxide can be chemically evolved.