A novel porous adsorbent was prepared by the in situ functionalization of porous chitosan-g-poly(2-acrylamide-2-methylpropane sulfonic acid) (CTS-g-AMPS) with polyaniline (PANI) and then used to remove Sr²⁺. The structure and morphology of the adsorbent was characterized by FT-IR, SEM, TEM and TG, and its adsorption properties were evaluated systematically by static and dynamic adsorption experiments. The maximum adsorption capacity of 88.95 mg/g for Sr²⁺ was reached within 40 min, which is better than most of the other adsorbents. Moreover, the porous adsorbent can be easily recovered and regenerated.