Reaction injection molding (RIM) is a rapid processing technique for the formation of polymer parts by direct polymerization in the mold. Polydicyclopentadiene (PDCPD)/Clay nanocomposites with various amounts of clay were synthesized with a Gusmer-Decker machine by RIM, and the specific injection conditions of the nanocomposites were obtained. The results of X-ray diffraction (XRD) diagrams of the nanocomposites showed that clay were completely exfoliated. The tribological behaviors of PDCPD nanocomposites were studied using an MM-200 friction and wear tester. The experimental results showed that the wear mass loss of nanocomposites reach the minimum while the MMT content of the nanocomposites is 1wt%. The values of friction coefficient almost keep constant within the range of MMT content as added.The worn surface of PDCPD nanocomposites was examined with a scanning electron microscope (SEM) and the friction and wear mechanism was discussed.