Fast-growing poplar has been widely planted in China. For the poor mechanical properties and large deformation of the timber, its application is greatly restricted. Modified fast growing poplar specimens with different plate thicknesses of 5, 10, 15, 20 mm, radial direction and chord direction), under different parameters were tested in this paper. The tests indicate that the failure gradually began by the single oblique section,then the horizontal crinkling failure occurs, finally to the double curvature failure and the single plate bending failure with gradual decrease of the plate thickness. In the compressive test of the modified specimens with different thicknesses, the mechanical properties of the modified specimens are improved greatly compared with the control specimens, the compressive strength, the peak compressive strain and the elastic modulus of the specimens increase significantly with decrease of the plate thickness. In the compression test of different texture combination modified specimens, the mechanical properties of chord and chord texture combination specimens are the best, followed by radial and radial texture combination specimens, and the lowest is chord and radial texture combination specimens. At the same time, the compressive strength, peak compressive strain and modulus of elasticity are significantly higher than those of the control specimens, and the compressive strength and modulus of elasticity of the modified specimens are lower than those of the control specimens.