<p>This study aimed to enhance the tribological and corrosion-resistance properties of copper-tin (Cu–Sn) alloy substrates by developing multilayer diamond-like carbon (DLC) coatings with different modulation periods. Gradient transition layers (Cr and Cr-WC composite) were first deposited, followed by WC-DLC/DLC coatings with four modulation periods (1, 2, 3, and 4) on the Cu–Sn substrates. The microstructure, tribological behavior, and corrosion resistance of the coatings were systematically investigated. Results indicate that the modulation period significantly affects both tribological and corrosion properties. The coating with two modulation periods demonstrated the best performance, exhibiting high bonding strength and a low friction coefficient of 0.044. This tribological improvement is attributed to an optimized internal structure, which, despite a slightly lower sp³ content (38.8%), effectively resists wear and spalling. Additionally, its corrosion current density is only 9.16 × 10^–8 A/cm², two orders of magnitude lower than the other coatings, indicating superior corrosion resistance. These results suggest that DLC coatings with appropriately designed modulation periods develop a dense microstructure with minimal defects, which is a key factor in enhancing corrosion resistance.</p>