A new composite, wood-polymer composite, was fabricated by formation of poly (methyl methacrylate) in wood cellular structure. Methyl methacrylate (MMA) monomer and a few of 2,2'- azobisisobutyronitrile (AIBN) as an initiator, as well as several drops of pyrimidine as catalyst were first impregnated into wood porous structure under a pressure condition, and then initiated for thermal polymerization through a catalyst-thermal treatment. The mechanical properties of the composite were tested, and the composite was also analyzed by SEM and DSC to further correlate its performance. The results indicated that the modulus of rupture, modulus of elasticity, compression strength and hardness of Wood-PMMA Composite were improved by 68.28%, 110.27%, 62.43%, 357% over those of Untreated Wood, respectively. The SEM observations showed that PMMA generated and filled up wood pores under the employed conditions, and thus reinforced the mechanical properties of wood. DSC analysis suggested that Wood-PMMA Composite was more thermal stability than Untreated Wood as the formation of PMMA within wood pores.