This study synthesized nanocomposite catalysts via a modification of Re/Pd codoped carbon nanotubes (CNTs) with different concentrations of polydopamine (PDA), which were used for perchlorate (ClO4) reduction. The loads, dispersion and reducibility of Re/Pd nanoparticles increased yet their particle sizes significantly decreased with the increase of PDA concentrations. The average diameter of Re/Pd codoped D2CNT (CNT modified by 2 mg/mL PDA) with a narrow size distribution was measured to be 2 nm. The ultrafine Re/Pd codoped D2CNT catalysts represented outstanding catalytic reduction activity for the conversion of ClO4 to Cl with TOF of 17.34 h(-1) under the room H-2 atmospheric pressure, which was about 8 times than that of the unmodified catalysts. Furthermore, PDA modification minimized the dissociation of Re by chemical bonding between Re and CNTs carrier and maintained good stability of nanocomposite. This study inspires us to apply green bionic methods to enhance the catalytic reduction of perchlorate by changing the physical properties of Re/Pd nanoparticles. (C) 2020 Elsevier Inc. All rights reserved.