We have studied a new method for the preparation of Th(IV)-imprinted chitosan-phthalate particles, which can considerably enhance the adsorption capacity and selectivity of thorium ions. In this study, chitosan-phthalate was used as the complexing monomer, Th(IV) as template, epichlorohydrin as crosslinking agent. Initially, chitosan was modified with phthalic anhydrides and complex formation occured between carboxylic acid functional groups and Th(IV) ions. Secondly, particles were crosslinked with epichlorohydrin. After the removal of Th(IV) ions, thorium solid phase extraction (SPE) on the Th(IV) ion-imprinted particles from aqueous solutions containing their different amounts, selectivity study of thorium versus other interfering metal ions mixture which are Fe3+, La3+, and Mn2+ and distribution and selectivity coefficients were reported here. A comparison of the selectivity coefficient of Th(IV)-imprinted chitosan-phthalate particles with the selectivity coefficient of non-imprinted polymers showed that the imprinted matrix for Th(IV)/Fe(III), Th(IV)/La(III) and Th(IV)/Mn(II) was 8.35, 8.75 and 10.81 times greater than non-imprinted matrix, respectively.