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[Display omitted] • A kind of organic solvent resistant and monovalent anions selective AEMs has been prepared. • The optimized AEM shows a low swelling ratio of 4.39% in DMSO at room temperature. • The perm-selectivity (Cl−/SO 4 2−) of AEM could reach 29.4 in a mixed solution containing DMSO. • The performance of AEM improves after protonation of PEI under acidic conditions. Solvent-resistant anion exchange membranes (AEMs) with a microphase separation structure have demonstrated the potential for efficient separation of monovalent and multivalent ions and solvent recovery. In this work, a kind of imidazole side-chain AEM based on poly(2,6-dimethyl-1,4-phenylene oxide) (BPPO) and crosslinking agent polyethyleneimine (PEI) was synthesized to achieve efficient separation of Cl− and SO 4 2− ions through electrodialysis (ED) in organic solvent systems. The as-prepared AEMs exhibit favorable dimensional stability in various organic solvents, such as 60 % DMSO (aq.), 60 % DMF (aq.), 60 % ethanol (aq.), and display outstanding ion separation performance for Cl−/SO 4 2− ions during the ED process. Specifically, the swelling ratio of the AEM in the organic solvents remains < 5.5 % for the AEM with a grafting rate of 60 % of 1-butylimidazole (BIm) on BPPO benzyl bromide groups. At a current density of 2.5 mA·cm−2 during the ED process, the perm-selectivity of Cl−/SO 4 2− ions can reach 72.1. Importantly, even in a mixed solution containing 10 % organic solvent and 0.5 M NaCl and Na 2 SO 4 (aq.), the perm-selectivity of Cl−/SO 4 2− ions could still remain at 29.4. This achievement can be attributed to the integration of BIm and PEI, which forms stable sub-nanometer ion channels within the AEMs, enabling selective separation of ions of different sizes in organic solvent systems. [ABSTRACT FROM AUTHOR]