Abstract: The influences of steam explosion and organosolv pretreatments on the cellulose content, crystallinity index, lignin content and hydrolysis of the triploid populous tomentosa under the optimal conditions were investigated in present study. Their impacts on hydrolysis characterizations of poplar substrate were studied, too. The results indicated that lignin could partly be removed by steam explosion pretreatment. In contrast, organosolv pretreatment can removed more lignin than that by steam explosion. The lignin was 63.34% lower than that of untreated one. The crystallinity index increased to 1.962 after steam explosion and to 1.712 after organosolv pretreatment compared to the raw material. The conversion rate of glucose was 81.36% after organosolv pretreatment and up to 91.29% after steam explosion.