Poplar is an important fast-growing species in China. The preparation of bio-ethanol with poplar wood as the raw material is a new attempt to solve today's energy problems. After steam-exploded pretreatment and then bacteria treatment to the poplar wood raw materials, the materials' chemical composition and properties were measured and analyzed. Through contrasting the changes of the materials' chemical composition(cellulose, lignin, hemicelluloses, extracts, ash and protein), the mechanism of chemical change of the tested materials in the...