Abstract: The upper seams of coal measures in Pingsuo mining districts in which Antaibu no.2 opencast is situated, have been strongly weathered and oxidized 。Some coal seams have been changed into the weathered coal and oxidized coal，even the claybeds derived feom these seams. Based upon the analyses of these coal seams the author has found some rules of the changes of low-rank gas coal attacked by the weathering and oxidation agents.By the quantitative analyses and statistical calculations, the parameters for classifying the types of coal in the weathered zone and oxidized zone have been determined.The factors controlling the processes of weathering and 0xidation have been also examined.