Ion chromatographic was used to determine the monosaccharide composition in rice straw with enzymes irradiation samples of lignocelluloses. First of all, the ordinary rice straw needs to be set under gamma radiation with 1 500 kGY intensity as pretreatment, hydrolyzed with hydrolase and then diluted with 20 mg/L solution of sodium azide(antimicrobial preservative). Then, let the solution go through the 0.22 m nylon membrane and OnGuard Ⅱ RP column (2.5 cc, by methanol and water) respectively. 1 mL effluent can be collected after discarding the initial 6 mL solution. Finally, the composition of monosaccharide should be measured by ion chromatography. The result was that the lignocelluloses hydrolyzes of rice straw was composed of the xylose, glucose, rhamnose, mannose and glucuronic acid monosaccharide, etc.