Abstract: Two natural samples,Chelsea soil and Paxton shale which have different organic content,chemical and physical properties each other,were chosen as sorbents for a sequential desorption experiment.The results show that while the major composition of organic matter of sorbent consists of humic acid(Chelsea soil),sorption of phenanthrene for soil sample is easy to get equilibrium and no clearly hysteresis exists between sorption and desorption.In reverse,for Paxton shale,because the organic matter is mainly made up by kerogean,hysteresis phenomenon could be observed,and sorption and desorption are a totally irreversible process.This implies that the difference of composition,structure and properties of organic matter of natural geo-sorbents is a major factor to control the environmental behavior of organic pollutants.