Nano-sized poly(vinyl acetate) (PVAc) particles were prepared by emulsification-and-diffusion method. Influences of process variables on the mean particle size of resulting sub-microparticles have been evaluated. It wasclarified that the type and concentration of stabilizer, homogenizer speed, and polymer concentration determined the size of PVAc sub-microparticles. Especially when didodecyl dimethyl ammonium bromide and propylene carbonatewere used as stabilizer and solvent, respectively. PVAc sub-microparticles smaller than 200 nm were obtained.