To improve lignocellulose energy-oriented use efficiency of the rice straw，rice straw was pretreated with phosphoric acid-acetone.The effects of particle size,materials to liquid ratio,temperature and time on enzymatic saccharification ratio of rice straw were studied.The construction of the rice straw was scanned before and after the pretreatment by SEM.The results showed that when the particle size of rice straw was ≤380 μm,the materials to liquid ratio was 1∶8,the pretreated temperature was 80 ℃ and the pretreated time was 1.5 h,the enzymatic saccharification ratio of rice straw increased from 18.6% to 65.4%.The crystalline structure of the rice straw was destroyed to pieces by SEM,providing good working conditions for the subsequent enzymatic saccharification.The research could provide an effective pretreated way of straw under mildness conditions.