In order to understand the adsorption behavior and evaluate the adsorption performance of Dibutyl phthalate (DBP) by different grain-sized suspended particulate matter (SPM), and identify the potential mechanism, the adsorption of DBP by different grain-sized SPM was studied by Batch equilibrium method. The in-situ SPM that collected from the Yulin River of the tributary of the Three Gorges Reservoir Area, was sorted into five grain-sized fractions (clay-very fine silt (<8 μm), fine silt (8~20 μm), medium silt (20~32 μm), coarse silt (32~63 μm) and sand (>63 μm)) via physical method of wet screening and natural settling in this study. The results showed that partition was the main mechanism of removal of DBP by SPM from the solution, and the adsorption capacity of different grain-sized SPM for DBP follows: clay-fine sand > fine sand > medium sand > coarse sand > sand. Total organic carbon (TOC) was the main factor affecting the partition of DBP by different grain-sized SPM. In addition, the difference of organic matter composition in clay-very fine silt SPM may be the reason for its high adsorption capacity for DBP. The specific surface area, pore volume and humification degree of organic matter affect its adsorption of DBP by silt-sand SPM.