［Objective］ To improve the service durability of the protective coating systems for concrete structures，a polydopamine（PDA）-based nano-bionic composite coating system was designed and evaluated.［Methods］ Two nano-bionic modified particles，denoted Pal@PDA（1∶ 4） and Pal@PDA（1∶1），were prepared by coating dopamine hydrochloride onto palygorskite（Pal）powder at different mass ratios. These particles were then incorporated into epoxy varnish and polyurethane varnish to formulate a nano-bionic epoxy sealing primer and a nano-bionic high-performance polyurethane topcoat，respectively. The effect of Pal@PDA（1∶1）on the mechanical properties and corrosion resistance of the polyurethane topcoat was examined. In addition，the chloride penetration resistance，artificial weathering resistance，and adhesion of the nanocomposite system were comparedwith those of a conventional epoxy primer plus polyurethane topcoat system.［Results］ The results show that incorporating Pal@PDA（1∶1） into the polyurethane varnish effectively enhanced the flexibility，adhesion，and alkali resistance of the coating film. At a Pal@PDA（1∶1）loading of 5%，the tensile strength and elongation at break increased by 24. 3% and 40. 3%，respectively，relative to pure polyurethane. For the nanocomposite system，in which both the primer and topcoat contained 5%Pal@PDA，the non-steady-state chloride migration coefficient decreased by 36. 6% and the glossretention after artificial weathering was increased by 12. 5% compared with the control system.Furthermore，the bond strength after 1 a of water immersion increased by 1. 5 times，reaching 4. 20 MPa.［Conclusion］ These findings demonstrate that the PDA-based nano-bionic compositeprotective coating system exhibits markedly superior service durability，providing an effective strategy for the long-term protection of concrete structures.