Layered clays have been used as reinforcement in polymer nanocomposites by having a structure of silicate layers, cation exchange capacity, organically modified and have high aspect ratios. The aspect ratio of these layers is defined by (ratio diameter/thickness) is particularly high, with values greater than 1000. In general, nanomaterials provide reinforcing efficiency because of their high aspect ratios. Kaolin is natural clay which is the characteristic clay mineral kaolinite that have chemical composition Al2O3.2SiO2.2H2O and as a 1:1 dioctahedral phyllo-silicate in nature. The distance between the silicate layers is 0.72 nm and the layer thickness is 0.437 nm. Nanocomposites that use kaolin presented excellent thermal properties, flame retardant, barrier and mechanical. Concerning the methods for polymer nanocomposites synthesis, the most employedare melt blending and in situ polymerization. In this paper, we studied the mechanism of kaolinite during the in situ emulsion polymerization toproduction of polystyrene nanocomposites filled with kaolinite. The polymer nanocomposites were characterized by X-ray diffraction (XRD), Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM) Ver menos