The initiator diffusion technique was used in this study to prepare the gradient index(GI) plastic rods, in which two kinds of initiators were used, i.e., thermal initiator and redox initiator. Experimental results showed that a GI plastic rod with a parabolic profile of refractive index was obtained by the initiator diffusion technique. The difference of the refractive index from the center to the periphery (DELTAn) of the plastic rods was in the range of 0.004-0.014. DELTAn increased with increasing temperature due to the increase of the gel effect and diffusion rates of monomers at a higher temperature. Futhermore, the GI plastic rod had substantially less defects, e.g., bubbles and opaqueness, than that prepared from interfacial-gel copolymerization.