A “dissolving and rebuilding” method was applied to prepare a diatomiteethyleneimine–polymer (PEI) hybrid composite, and its structure and topography were characterized by XRD, SEM, TEM, FTIR, DTG, elemental analysis and ζ-potential. The results indicated that the PEI was efficiently assembled into the SiO₂ framework formed from diatomite. Attempts were made to use the composite to remove phenolic pollutants, e.g. phenol, o-chlorophenol and bisphenol A (BPA), from aqueous solution. These adsorptions were to be in accordance with lipid–water-partition law, and their K_aw values were calculated to be 79.1 L kg⁻¹ for phenol, 37.3 L kg⁻¹ for o-chlorophenol and 24.2 L kg⁻¹ for BPA.