In this paper,the natural illite is used as low-cost sorbent for investigating the sorption of Th(IV). The sorbent is characterized by titration, N2-BET, FTIR, XRD, SEM/EDS and XPS. The sorption behavior of Th(IV) on the sorbent is investigated by batch method. The kinetics of Th(IV) adsorption process on the sorbent is fitted well by the pseudo-second order rate equation. The sorption capacity of Th(IV) is increased with the solid-to-liquid ratio increasing. The sorption of Th(IV) is strongly dependent on pH(pH< 5) and ionic strength. The negative effects on sorption of cations shown from strong to weak is: Mg(NO₃)₂?KNO₃?NaNO₃. The influence of the anions are: PO₄ ^3- obviously promoted Th(IV) sorption, while the existence of SO₄ ^2- inhibited Th(IV) adsorption. Gibbs free energy (ΔG0 ), Enthalpy (H0) and entropy (ΔS0) and are calculated from the temperature-dependent sorption data and the results indicate that the sorption of Th(IV) on natural illite was a spontaneous process. Isotherms of Th(IV) adsorption to natural illite could be described well by Langmuir model. Through the desorption experiments, the adsorption process on natural illite was reversible reaction. The sorption mechnism of Th(IV) on natural illite is ion exchange reaction with its potassium ions that are trapped in its interlayer spaces; as well as outer sphere complexes formation (pH< 5) and inner sphere complexes(pH>5) through =Si-O- and =Al-O- groups are located at the edges.