Four copper-film-plated steel cords (abbreviated hereafter as copper-plated cord) with different thickness of copper film from 32 to 90 nm were prepared and their adhesion properties with rubber compound were investigated. Adhesion properties improved with the decrease in the thickness of the copper film. Unaged pull-out force and rubber coverage of copper-plated cords were inferior to those of brass-plated cord, but adhesion degradation was significantly slower on copper-plated cords resulting in better adhesion after humidity aging of 15 days and salt solution aging of 5 days. The excellent adhesion stability of copper-plated cords can be explained by the suppression of the excessive growth of copper sulfide and the inhibition of dezincification due to the small amount of copper plating and the lack of metallic zinc at the outer surface.