Abstract: Benzimidazole polymer adsorbents, PS-MBI was prepared through grafted 2-mercaptobenzimidazole on the matrix of chloropolymer. It was used for selective recovery of Pd(Ⅱ) from chlorinated medium. Optimization of adsorption separation parameters was studied. The adsorption separation mechanism was also discussed. The research result shows that PS-MBI has excellent adsorption effects on Pd(Ⅱ) in 0.1 mol/L hydrochloric acid solution. The maximum adsorption capacity was 138.8 mg·g⁻¹. PS-MBI can separate Pd(Ⅱ) from the mixed solutions containing Pd(Ⅱ), Pt(Ⅳ), Rh(Ⅲ), Cu²⁺, Ni²⁺, Fe³⁺ and Zn²⁺. The separation of palladium from metal mixture solution can be accomplished in one step. The separation coefficient of Pd/M (M: Pt, Rh, Cu, Ni, Fe, Zn) is higher than 1.0×10³. PS-MBI has good reuse performance. After three adsorption-elution cycles, the recovery rate of PS-MBO adsorption Pd(Ⅱ) was higher than 92.0%. FT-IR and XPS show that PS-MBI adsorb Pd(Ⅱ) as the coordination mechanism. Pd(Ⅱ) was separated from the mixed solution of metal ions by forming coordination bonds with the N atom on imidazole rings.