Abstract:The determination of the mechanical behavious of the flakes in compression stress, from three popular species—hybrid Populus spp., Populus tomentosa, Populus euramericana cL‘cima‘ showed that some different rheological characteres tics of significance existed among them. It could be consideral that the different rheological characteristics resulted in the different properties of particleboard from these popular species. The 0.35mm thickness flakes of hybrid popular with mechanical behaviour characerized by weak strength of spring back resulted in rapid increase of MOR and no considerable increase of IB with increase of board based on compression ratio from 1.2 to 1.5. In the range of high density of board, the dimensional stability decreased. When the thickness of the flakes were changed to 1.2mm, MOR and IB increased synchronously because of their stronger spring back strength. However, thicker flakes resuled in lower E-module and poor dimensional stability. The flakes of the other two species performanced rather better elastic behavour and lower engagement coefficient in compression stress than that of hybrid popular flake. The density of particleboard from the other two species with 0.35mm thickness increased in a wide range of compression ratio, both MOR and IB increased considerably, and the dimensional stability still keep in a stable level.