Abstract: Quick coal liquefaction at high temperature (QCLHT) was studied by using a 17mL tubular resonance agitation microautoclave reactor. The results show that a low rank bituminous coal containing little mineral matter exhibits good liquefaction performance. The conversion is mainly influenced by hydrogen-donating ability of solvent and contribution of H₂ is negligible. The conversion under N2 atmosphere is basically equal to that under H₂ atmosphere. Effect of catalyst is not remarkable. Coal particle size has little influence on conversion, whereas vibration of reactor has important influence. Based upon the above conclusions, the reaction mechanism of QCLHT was suggested. At high temperature zone of the primary pyrolysis of coal, usually near 500℃ or so, bridge bonds in its structure are sufficiently broken for low rank bituminous coal, and large amounts of free radicals are thus formed. If enough excellent hydrogen donor solvent is used as hydrogen source, the free radicals could be stabilized and formed into liquid product. Hence, rather high conversion is achieved within dozens of seconds or a few minutes.