Abstract: Bio-oil produced by rapid pyrolysis of biomass can be used as fuel and chemical products has great potential to replace fossil energy. The yield and composition of bio-oil depend on biomass composition and process parameters. This paper introduces biomass rapid pyrolysis reaction and pyrolysis reactor, focus on discussion of the effects of biomass raw materials, pyrolysis reaction temperature, pyrolysis time, heating rate, steam residence time, feed rate speed, particle size, biomass composition, catalyst and its raw material pretreatment on bio-oil yield were discussed emphatically in order to provide reference for the related research of biomass pyrolysis in the future.