Abstract: This paper analyzes the organic carbon isotope abundance of 19 coal samples from 7 coal seams in Tunlan coalmine, Xishan coalfield, and studies the distribution characteristics and changing trend of carbon isotope value （δ¹³Corg） among various coal seams. The research results show that δ¹³Corg values in Tunlan coal range from -25.6‰ to -23.3‰, with an average value of -24.3‰. The δ¹³C values of 9 coal to 02 coal (from bottom to top) showed a generally positive trend, with only 7 coal showing a negative trend. The increase of δ¹³Corg in coal may be influenced by the temperature rise in the Permian North China region. With the increase of maturity, the δ¹³Corg-Rmax correlation curves of different coal seams show a certain positive correlation. The polynomial regression function model was used to determine the relationship between δ¹³Corg-Rmax.