Disclosed is a method for forming a polymer nanocomposite, which comprises (a) modifying a clay material comprising layered silicate particles by ion exchange with a surfactant to form an organoclay; (b) dispersing the organoclay in a vinyl monomer and bulk polymerizing said monomer in the presence of a catalyst; and (c) adding a liquid suspension to the above mixture to effect suspension polymerization when the conversion rate of the polymerization is about 10% to 50%, thereby forming a composite having the particles uniformly dispersed in a vinyl polymer matrix.