Abstract: The gas in the Upper Paleozoic main coal seams of the southem Shanxi is relatively rich in the southern and eastern indicated areas relatively poor in the northern and wesern areas and richest in the southeastern area,and its distribution seems to be controlled by the seam horizons。The gas contents are showed as the functions of the coal rank and ash yield。Based upon the gas-bearing characteristics,the main seams could be classified into three categories including six types,in which the rich-gas and bearing-gas seams occur mainly in the southern indicated areas and the deep referred predicted areas,where the further evaluation of the CBM resources would be valuable。