【Objective】Bentonite is a cheap and efficient adsorbent that reduces the mobility of organic and inorganic pollutants in soil.Once chemically modified, the bentonite can increase its organic pollutantsadsorption capacity. As organic pollutants are different in hydrophobicity, they are adsorbed by different mechanisms, such as distribution, surface, charge attraction,even on the same surface. However, the current researchesare focusing mainly on single surface modification of bentonite adsorbing a single organic pollutant, with little attention to complex amphoteric anionic compound modified bentonite adsorbing organic pollutants different in hydrophobicity on its surface via different mechanisms and its causes.In this paper, Dodecyl dimethyl betaine(BS) modified bentonite was remodified with anionic surfactant Sodium 1-decanesulfonate (DAS). Analysis was done of effects of modification rates on adsorption capacity of the modified bentonite and its apparent thermodynamic parameters of phenol and phenanthrene, and further of differences in adsorption of organic pollutants different in hydrophobicity and its causes.【Method】Sodium bentonite was purchased from the Xinyang Tongchuang Bentonite Company and further purified . BS is an amphoteric surface modifier and DAS an anionic surface modifier. BS modified bentonite and BS+DAS combined modified bentonite were prepared with the wet method. 50BS means that the modification ratio of BSis 50% CEC, whereas 100BS+100DAS means indicates that the modification ratio of both BSand DAS was 100% CEC. Phenol and phenanthrene had 9 levels of concentration forming a gradient. A batch adsorption experiment was done, placing 0.2000g of soil sample into each 50mlcentrifuge tube (plastic or glass), adding 20.00mlof phenol or phenanthrene solution (25% v/v, Dimethyl sulfoxide as solvent), separately into plastic tube or glass tube, covering each tube with a lid andsealing the lid with glue to prevent volatilation of phenol and phenanthrene,putting the tubes on an oscillator with constant temperature for 24 hours of oscillation and then on a centrifugeforcentrifugation, determining equilibrium concentration of phenol or phenanthrene in the supernatant, and in the end calculating adsorption of phenol or phenanthrene in the solution using the subtraction method.【Result】Results show that adsorption of phenol and phenanthrene on BS+DAS bentonite decreased with increasing anionic modification ratio, the effect of the BS+DAS bentonite inhibiting phenol adsorption was more significant; the sorption of phenol on the bentonite were of the mode of “unsaturated” partitioning, while the sorption of phenanthrene of the mode of “saturated” partitioning; and both were physisorption. rising temperatureinhibited the sorption of both, but rising pH promoted the adsorption of phenol while inhibiting the adsorption of phenanthrene; Ionic strength, in the solution varying in the range of 0.001 molL^-1~0.1 molL^-1 KNO₃in concentration, enhanced phenol and phenanthrene adsorption; the analysis of thermodynamic parameter shows that the adsorptions of phenol and phenanthrene on BS+DAS bentonite were spontaneous process, while the adsorptions triggered by improvement of the logarithmic n-octanol/water partition coefficient (log P) by DAS on the surface of BS+DAS bentonite were different in mechanism.【Conclusion】To improve the soil sample’s capacity of adsorbing organic pollutants different in hydrophobicity by modifying the soil sample chemically to increase its organic carbon content, it is essential not only to take into consideration the effect of organic carbon content, but also to take into account variation of the intermiscibilitybetween organic phase of the soil surface and pollutions.