Poly(ethylene-co-vinylacetate)(EVA) microspheres were prepared by thermally induced phase separation in toluene. The microsphere formation occurred by the nucleation and growth mechanism in metastable region. The effects of the polymer or pigment weight percentage and cooling rate on microsphere formation were investigated. The microsphere formation and growth were followed by the cloud point of the optical microscope measurement. The microsphere size distribution, which was obtained by particle size analyzer, became broader when the polymer concentration was higher, the pigment concentration and the cooling rate of EVA copolymer solution were lower.