Abstract: In order to improve the biological saccharification efficiency, rice straw was pretreated with sodium hydroxide and alkaline hydrogen peroxide, respectively. The effects of liquid concentration, temperature and time were used to investigate the effectiveness of the two pretreatment methods were investigated. Moreover, the effect mechanism was revealed by analyzing the changes in structure and composition of rice straw before and after the pretreatment. The results showed that under the condition of 80 ℃, 1.25% sodium hydroxide had a better effect on rice straw after 3 h water bath treatment, and the reducing sugar content was 480.81 mg/g after 72 h enzymatic hydrolysis. Under the condition of 50 ℃, the effect of alkaline hydrogen peroxide (1.5% NaOH, 2% H₂O₂) on rice straw after water bath for 5 h was better, and the reducing sugar content was 575.85 mg/g after 72 h enzymatic hydrolysis. The reducing sugar yield from rice straw with sodium hydroxide and alkaline hydrogen peroxide pretreatment increased by 262.3% and 336.2%, respectively, compared with rice straw without pretreatment (132.7 mg/g). Scanning electron microscope analysis indicated that the specific surface area of rice straw pretreated with sodium hydroxide and alkaline hydrogen peroxide increased obviously, and the structure became looser and porous. Fourier transform infrared spectrum and X-ray diffraction spectrum analyses showed that after sodium hydroxide and alkaline hydrogen peroxide pretreatment, the lignin in rice straw was digested into cellulose, which improved biological saccharification efficiency.