Soluble organic matter is separated from the palygorskite samples collected from Linze area in Gansu Province, China. Its composition is analyzed and the ratio of stable isotope 13C in typical samples is determined. The results show that the soluble organic matter abundance in rock sample is low. Gas chromatogram distribution of hydrocarbon in Linze samples reflects that original biological material comes from terrestrial higher plant as well as from aquatic biological source partly, with average δ13C of organic matter in palygorskite of -18.74‰.