To ensure good compatibility between polymer and montmorillonite (MMT), three types organophilic-MMT were prepared and the influence of modifying agent style on the modification effect was studied. The results of X-ray diffraction(XRD) show that the modified reagents are all intercalated into the galleries of MMT, which are also proved by patterns of FT-IR and thermogravimetric analysis(TGA), and the spacing of MMT layers increases from 1.23 nm of the pristine MMT to 2.10nm, 3.52nm and 4.14nm for CTAB, SDS and DBS modified MMT respectively. The results also indicate that the d-spacing and exfoliation degree of anionic surfactants inserted MMT is bigger than that of the cationic surfactants treated MMT, which are usually used to preparation polymer layered silicate nanocomposites in literatures. So PS/SDS-MMT and PS/DBS-MMT nanocomposites were prepared by suspension polymerization. The structure of complex were characterized by XRD and no peak can be observed by the spectra, which suggest that the clay platelets have been exfoliated and dispersed in the PS matrix and the both complex are all have exfoliated structure. FT-IR spectrums analysis confirmed the existence of MMT which implied that the layers of silicate was distributing in composites. The results of TGA show that nanocomposites possess exceptionally high thermal stability and the DBS treated composite has higher thermal stability than that of SDS treated.