Poly(methyl methacrylate) (PMMA) particles, denture base resin, were synthesized by suspension polymerization through control of polymerization conditions (stabilizer concentration, co-monomer concentration, and the agitation speed) and evaluated changes in molecular weight and particle size. We also investigated their mechanical properties of compression-molded samples which were from synthesized polymer powder mixed with methyl methacrylate (MMA) solution. under the condition of volumetric ratio as 2:1(PMMA powder and MMA solution). The results shows that the mechanical properties were mainly affected by particle size over 100 ${mu}$m (in particle size) and by molecular weight under 100 ${mu}$m (in particle size). From these results, we concluded that the most appropriate particle size of PMMA powder for heat-cured denture base resins is around 100 ${mu}$m. and its molecular weight is around 300000 (M$sub$n/).