Abstract: The formation of acetylene by coal plasma pryolysis is strongly dependent on coal properties. The purpose of this paper is to elucidate the effects of coal properties on the acetylene formation and coking in plasma pyrolysis in H2/Ar. 12 kinds of coals with different coal rank were chosen and the effects of coal properties, including the content of volatile matter, oxygen and ash, on the yields of acetylene and coking were investigated in details. The results show that the bituminous coals containing the volatile matter from 30% to 40% have higher acetylene yield, while the coals with high oxygen content have lower acetylene yield, which corresponds to an increase in carbon conversion to carbon oxides. The content of mineral matter in coal has no significant relationship with the acetylene yield though it would increase the formation of CO. The higher mineral-matter content in coal is found to have a specific effect on the coking. The results of the tests by adding SiO2 and sands indicate that the high content of mineral-matter would increase the coke formation and affect the configuration of coke.