Synthesis of carbon nanotubes and nanofibers on a metal substrate by an ethylene fueled inverse diffusion flame was illustrated. Stainless steel plates were used for the catalytic metal substrate. Multi-walled carbon nanotubes and nanofibers with a diameter range of 30-80nm were found on the substrate. The temperature of the substrate played an important role in the formation of carbon nanotubes and nanofibers. The pathway to the nanotubes and nanofibers could be determined by the temperature history of the substrate.