A polymerizable nonionic emulsifier, hydroxyethyl acrylate-2, 4-diisocyanatotoluene-polyethylene glycol (HEA-TDI-PEO), was designed and synthesized to explore its role in the stabilization of miniemulsion system. The hydrophilicity and solubility in oil or water of HEA-TDI-PEO can be controlled by adjusting the molecular weight of PEO and the total molecular weight. It was found that HEA-TDI-PEO could combine the function of emulsifier and costabilizer, which would be solely used to prepare stable St miniemulsion. The stability of the miniemulsion system with HEA-TDI-PEO with different molecular weight and concentration were investigated by dynamic light scattering, transmission electron microscope and X-rays photoelectron spectroscopy analysis. The kinetics of the polymerization of St, which was initiated by 60Co ?-rays, is in accord with droplet nucleation mechanism. Only 2%–2.5% weight percent of HEA-TDI-PEO(1900) based on the monomer can form a stable miniemulsion and further result in uniform PS latex particles.Cited