Nanocomposites based on ethylene-propylene-diene rubber(EPDM) and montmorillonite have been prepared via a melt process by using two vulcanization systems：a sulfur-accelerator system and a peroxide curing agent DBPH The results of X-ray diffraction (XRD) and transmission electron microscopy (TEM) showed that

the rubber molecules were found to be intercalated into the galleries of the organophilie montmorillonite (OMMT)

and the silicate layers were exfoliated and dispersed uniformly in the rubber matrix of the nanocomposite cured bv the sulfur-accelerator system

but the silicate layers were stacked and existed in the form of intercatated structure in the nanocomposite cured by the peroxide agent DBPH The exfoliated nanoeompesites were was opaque and had better mechanical properties than the intercalated ones which were semi-transparent The two kinds of curing systems had different curing behavior evaluated by the Flory-Rehner equation The vulcanization time (t90) was prolonged

and the maximum-minimum torque (MH-ML) decreased with increasing of OMMT content．and the EPDM become less erosslinked in the presence of OMMT for nanocomposites cured by sulfur curing system However

the corresponding values of the nanoeomposite cured by peroxide agent DBPH did not change obviously with the OMMT content.