Abstract: Ethylene-propylene-diene(EPDM)/OMMT nanocomposites were prepared with a new type OMMT through two-roll blending.The results of transmission electron microscopy(TEM) observation showed that the particles of OMMT were interca-lated or exfoliated in the EPDM matrix.The mechanical properties testing results indicated that as the filler loading below 15 phr the mechanical properties of OMMT system were higher than those of carbon black system.The tensile strength of the EPDM/OMMT nanocomposites at the filler content of 10 phr reached 15.85MPa,that is the 2.4 times of carbon black system and more 7 times of neat EPDM system respectively.The tear strength of OMMT was higher than that of carbon black,simul-taneously the shore A hardness of the OMMT system is 10 lower than that of carbon black system at the same strength.