Abstract: Sawdust was pyrolyzed in a bench-scale fluidized bed and the mass balance of pyrolysis reaction was calculated. By installing an electrostatic precipitator (ESP) in the end of the fourth condenser，bio-oil yield increased from 54% to 72%，which not only prevented bio-oil from losing together with the produced gas，but also made the gas cleaner. When the pressure of condensers was maintained at a level of 100 Pa，the yield of bio-oil reached the maximum. Energy consumption of the pyrolysis process of sawdust was measured as about 2.01 MJ/kg. The chemical compositions of bio-oil were analyzed and classified with GC/MS and their physical properties were charactered.