Abstract：In order to prepare large size ( nearly 20 μm) , monodisperse polystyrene ( PS) micro-spheres, PS seed microspheres were prepared by dispersion polymerization method, and then PS microspheres was prepared by multistep seed swelling method. The effect of PVA concentration on the particle size and monodispersity of PS microspheres were discussed, and the effect of the inhibitor NaNO₂on the secondary particles was discussed. The results showed that the diameter of seed PS microshperes was 3. 15 ( ± 0. 13) μm. In each step of the seed swelling process, the particle size of PS microspheres decreased gradually, and the variation coefficient ( Cv) decreased first and then increased with the increase of PVA concentration. The addition of NaNO₂could effectively inhibit the generation of secondary particles. The average particle diameter and Cvof PS microspheres prepared by the three-step seed swelling was 18. 76 μm and 0. 209, respectively.

Keyword：multistep seed swelling procedure;micron-large-sized particle;monodisperse;polystyrene microsphere;