A novel method for preparing gradient refractive index (GRIN) plastic rods by using the centrifugal diffusing polymerization (CDP) technique has been developed in this investigation. Methyl methacrylate (MMA) and diphenyl sulfide (DS) were used as reactive monomer and unreactive dopant, respectively. 2,2'-Azoisobutyronitrile (AIBN) was used as the initiator. Effects of feed weight ratio of MMA/DS, added amount of acrylic polymers, and preparing conditions on the optical characteristics of the plastic rods were investigated. The refractive index distribution and the image transmission of the GRIN rods were estimated.