Abstract: Rice straw pretreatment in high temperature conditions were optimized to improve the enzymatic hydrolysis yield of reducing sugar.The effect of solid-liquid ratio, pH, temperature, time to the sugar yield were investigated .By multilevel of single factor test and orthogonal test methods, the results for the optimal pretreatment conditions were as follows:the solid-liquid ratio of 1∶8, pH12, 190℃, 15min.Under the optimal condition, the reducing sugar yield was 88.97% after enzymatic hydrolysis .