The carbon nanotubes (CNTs) reinforced Al-Cu matrix composites were prepared by hot pressing sintering and hot rolling, and the effects of Cu content on the interfacial reaction between Al and CNTs, the precipitation behavior of Cu-containing precipitates, and the resultant mechanical properties of the composites were systematically investigated. The results showed that the increase of Cu content can not only increase the number and size of Cu-containing precipitate generated during the composite fabrication processes, but also promote the interfacial reaction between CNTs and Al matrix, leading to the intensified conversion of CNTs into Al₄C₃. As a result, the composite containing 1 wt.% Cu possesses the highest strength, elastic modulus and hardness among all composites, due to the maintenance of the original structure of CNTs. Moreover, the increase of Cu content can change the dominant strengthening mechanisms for the enhanced strength of the fabricated composites.