A co-pyrolysis experiment of coal and natural gas was investigated on a fixed-bed reactor. SEM was used to study the structure changes of the exterior surface of char prepared in this co-pyrolysis experiment, while GC was also utilized to analyze the associated gas. The result showed that, with increasing temperature, the coal char tended to agglomerate. GC and SEM results show that the CH4 decomposition on the exterior surface of char was turned to filamentous char and extended around like coral. It was also proved that the co-pyrolysis of coal and natural gas promoted syngas production. A synergistic effect of coal and natural gas does exist during this process.