This work applied coal tar as a potential kind of feedstock in thermal plasma pyrolysis process, by which effective transforming from coal tar to acetylene could be realized in milliseconds. A kilowatt level lab-scale plasma pyrolysis device for coal tar pyrolysis was established. Experiments with three typical coal tars were carried out to investigate the influences of operating parameters on the feedstock conversion and the yields of total light gas and acetylene. The results show that low-temperature coal tar has the best pyrolysis performance, with the highest light gas yield exceeding 70 % and acetylene yield of 45 % when using Ar plasma. Considering both conversion and energy efficiency, 6.0 x 10(4) kJ/kg is regarded as the most appropriate specific energy input for coal tar in Ar/H-2 plasma, which promises a conversion of 65 %. Further discussion was made that coal tar has better pyrolysis properties than coals.