A novel screw-type reactor for the fast pyrolysis of agricultural waste (flax shive) is described. A preliminary study on the influence of process parameters on the yield, composition, and properties of pyrolysis products was carried out. Based on the results obtained, the optimal conditions of fast pyrolysis of flax shive particles in terms of feedstock particle size, solid residence time, and process temperature were identified. Considering the construction, the developed reactor seems to be close to the screw fluidized bed and auger reactor and is characterized by a simple design and operation control. Moreover, the proposed reactor can be used for continuous pyrolysis without any significant modification.