To address the unclear effects of quenching-polishing-quenching (QPQ) treatment on the performance of nickel-aluminum bronze alloy coatings welded onto 27SiMn alloy steel, this study investigated the geometric characteristics, microstructural changes, corrosion resistance, and hardness of the copper alloy coating. The influence of the QPQ treatment process on the coating’s microstructure and properties was analyzed to verify the rationality and feasibility of this composite anti-corrosion technology. The results indicate that after undergoing the two processes of carbonization/nitriding and oxidation, the copper alloy coating forms a dual-layer infiltration structure, with metal carbides distributed across both layers and copper oxides concentrated near the surface, providing corrosion protection. Before and after QPQ treatment, the microstructure of the copper alloy coatings primarily consists of the matrix phase α, the metastable phase, and various κ phases dispersed within the α phase. High-and medium-temperature tempering leads to the precipitation of a large amount of β' phase into the α phase, causing the matrix phase to coalesce and expand while reducing overall hardness. According to the protection rating representation method based on the proportion of substrate area affected by corrosion, the protection rating of the surface of the copper alloy coatings layer samples is 9, while the copper alloy samples after QPQ treatment is 10. The corrosion resistance of the copper alloy surface after QPQ treatment is not only maintained but also exceeds that of the untreated one. In light of this, the composite anti-corrosion technology can be applied to the maintenance and remanufacturing of hydraulic bracket cylinder barrel parts, which can enhance the corrosion resistance of the inner wall of the cylinder barrel as a whole, while also considering the corrosion resistance of other parts such as the joint holes and the outer surface of the cylinder body.