Quenching is a key approach to obtain high acetylene yield in the process of coal tar pyrolysis to produce acetylene in a thermal plasma reactor due to the thermodynamic characteristics of acetylene. Experiments of coal tar pyrolysis were carried out in a lab-scale H-2/Ar plasma reactor under various quenching conditions. Meanwhile, thermodynamic analysis was performed to assist the optimization of quenching temperature and the maximization of acetylene yield. As quenching media in the experiments, hydrogen, argon, methane, and water were used separately to study the influence of quenching process on acetylene yield and specific energy requirement. The experimental results indicate that the acetylene concentration in quenched product gas was significantly affected by quenching operation, and the acetylene yield was significantly affected by quenching medium flow rate. The acetylene yields of 24.6, 17.8, 44.9 and 23.6 wt% can be reached by using hydrogen, argon, methane, and water as quenching media, respectively. The specific energy requirement analysis indicates that process energy efficiency can be improved by a suitable quench operation.