RF thermal plasma(RFTP) had been utilized for synthetizing ultra-fine ZrC powders with different carbon sources, such as carbon black and methane. The products of the experiment were characterized by XRD, IR absorption, SEM, and chemical analysis. The results demonstrated that the ZrC powders which were less than 100 nm in the average diameter could be obtained with both carbon sources. However, methane played a better role than carbon black in the purity, the oxygen content and the productivity of ZrC powders. So, as a carbon source, methane was more applicable for batch preparation of ultra-fine ZrC powders.