Expanded graphite treated with silane coupling agent (DB-171) was incorporated into PDCPD to explore its tribological features. Chemically treated expanded graphite (TEG)/PDCPD composites were prepared by a simulating reaction injection molding (SRIM) system. The friction and wear properties of TEG/PDCPD composites were investigated on a block-on-ring tribological tester under dry sliding condition. Experimental results show that the friction coefficients of PDCPD composites increase slightly, and the wear volume losses of the PDCPD composites reduce significantly with the loading of treated expanded graphite. The addition of only 0.3wt% chemically treated expanded graphite contributes to dramatic improvement of wear resistance of PDCPD, and the wear volume loss reduces by 71.2% compared with pure PDCPD. Scanning electron microscopy (SEM) was utilized to study the worn surfaces of PDCPD composites, and the friction and wear mechanisms were discussed.