On the basis of pyrolysis and combustion tests on drop tube furnace (DTF), it has been substantiated the existence of amount of less combustible constituents (LCC) in Yangquan coal. They generally lie in the separation fractions with specific density. In combination with thermogravimetrical analyses on a Du Pont 2100 thermal balance, measurement of particulate diameter of chars and burnout carbons (BC) on a Malvern Mastersizer instrument, and numerical calculation by mathemetical models, kinetical parameters, like apparent pre-exponential factor (k(0)) and activation energy of reaction (E) of Yangquan raw coal and three separation fractions with different density have been obtained. The results show that parameters of LCC are always less than that of the others.