Sorption isotherms of pyrene on soils and sediments were obtained to understand its sorption behavior. All systems examined exhibited nonlinear isotherm and Freundlich model fitted the experimental data better than Langmuir and linear models. The sorption nonlinearity was found to be a function of polarity index of soil/sediment organic matter (SOM), which suggested that the degree of condensation of SOM characterized by its polarity index was closely correlated with sorption behavior of pyrene, and the polarity index of SOM could be a new factor for explaining the sorption nonlinearity. The sorption affinity of studied SOM for pyrene increased with decreasing polarity. A higher sorption affinity of SOM associated with two soils of higher degree of condensation compared to two sediments was observed, which suggested that the SOM in the two soils examined would more significantly decrease the bioavailability of pollutants thus leading to difficulties in bioremediation and likely enhancing their sequestration in soil matrix. A displacement test was performed after pyrene sorption using phenanthrene as a displacer. The results indicated that the principal solute pyrene was obviously displaced in all systems examined, and the nonlinearity of its sorption isotherms became less pronounced after displacement. Such an increase in isotherm linearity implied that sorption sites energies became more homogeneous after displacement. Furthermore, the site energy distribution F(E*) derived based on Freundlich model parameters showed that energy reduction of high-energy sites was more significant than that of low-energy sites after displacement. In addition, a decrease in the sorption capacity after displacement could be ascribed to the partial depletion of sorption sites by displacer. The displacement results showed that the co-contaminant of similar structure would have potential effects on transfer, fate and bioavailability of anthropogenic organic pollutants sorbed on soils and sediments, thus affecting their exposure risks.