Inspired by the multi-level physiological structure of wood cell wall, a bionic method accomplished by annular thickening of cell wall by polymer was proposed to improve the mechanical performances of plantation wood. The thickening mechanism and the contribution of annular thickening of cell wall to the mechanical performances of plantation wood was analyzed. Results indicated that wood cell wall could be annularly thickened by the modification system prepared with water-soluble vinyl monomers and organic solvent. The flexural, compressive and impact strengths of plantation wood were synchronously improved after the treatment. The modulus of rupture of the prepared wood with 22.4% weight percentage gain reached up to 95.7 MPa which was higher than the TB 17 requirement based on the Chinese National Standard (GB 50206). The thickening degree which could be controlled by adjusting modifier concentration was closely related to the mechanical performance of treated wood.