Abstract: Ultrafiltration composite membranes exhibit great potential for Ag⁺-containing wastewater treatment, however, the ultrafiltration process is still limited by the trade-off effect between permeability and retention rate. In this work, the polymer poly-3,4-ethylenedioxythiophene:polystyrene sulfonic acid (PEDOT:PSS) was coated onto the polyethersulfone (PES) substrate by vacuum filtration for the retention of Ag⁺ in wastewater. By regulating the thickness of PEDOT:PSS separation layer, the operating pressure and the initial concentration of Ag⁺, the optimal water flux of 106.1 L m⁻² h⁻¹ bar⁻¹ with 100% Ag⁺ retention at 5 ppm concentration is obtained for PEDOT:PSS@PES composite membrane. It is noteworthy that Ag⁺ is reduced to Ag(0) during ultrafiltration process. These results emphasize that introducing polymer into ultrafiltration membrane can absorb and reduce Ag⁺ at high permeate fluxes, which offers a new possibility for the treatment of Ag⁺-containing wastewater.