Abstract: In order to get high xylose yield from the hydrolysis of dilute acid pretreatment straw, the effects of single factor reaction time, solid-liquid rate and concentration to the pretreatment process were investigated. Meanwhile, the treatment conditions were optimized with quadratic regression orthogonal design. The orthogonal design was set up, which was fit to the linear between factors and xylose yield. Variance analysis exhibited a significant difference. Moreover, the order of the factors was as follows: reaction time (x1)> liquid to solid ratio (x2) > concentration of acid (x3). Using the regression equation model, the optimal pretreatment conditions were determined: reaction time 2 h, concentration of acid 4.1%, liquid to solid ratio 22:1. Under the optimal conditions, the xylose yield was 0.332 g/L. The quadratic regression orthogonal design had the advantages of less test times and optimized pretreatment conditions for the basis studies. The results of this study showed that the effects of three interaction items were not significant, but the coded factors of reaction time and acid concentration needed to be adjusted.