To increase the use of lignite, the tar was pyrolyzed with pyrolysis coke (PC) to produce more combustible gases such as H-2, CH4, and CO. NiO/PC catalyst with plasma was prepared, and the influence of PC and NiO/PC catalyst on flammable gas was investigated in a two-stage fixed reactor. The catalysts were characterized by SEM, BET, XPS and XRD to analyze the tar cracking mechanism. The results were: (1) PC was prepared at different heating rates, and when the heating rate reached 20 degrees C/min, the amount of flammable gas was 5.4 L. (2) NiO/PC catalyst was modified with plasma in three background gases withO(2) being the best, mainly because of the increase of the oxygen functional groups. (3) PC was modified and calcined with plasma, and when the power reached 40 W, it produced the most combustible gas, and the volume could grow by 94.4%. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.