Abstract: Bamboo fiber was pretreated by 1-butyl-3-methyl imidazole chloride salt(Bmim Cl)/ethanol mixture solvent. The optimum conditions for the dissolution were as follows:volume ratio ofBmim Cl/ethanol of 5:12, deionized water content of 4% and reaction process at 160℃for 12 h. The bamboo fiber dissolution yield could reach 18.14%, with residual cellulose product yield of 81.84%. The chemical structure was confirmed by TG-DTG, FT-IR and XRD. The TG-DTG results showed that the ionic liquid had good thermal stability and did not decompose at 160℃ in this experiment. Meanwhile, XRD results revealed that the crystallinity index increased from 26.54% to 31.21%, exhibiting the typical cellulose I crystalline structure; FT-IR analysis showed that the structure of regenerated cellulose did not change significantly during the separation process.