Abstract Copper/low-density polyethylene (Cu/LDPE) composite is a novel copper intrauterine devices (Cu-IUDs) material; the aim of this study is to report its anti-aging properties. After the prepared composite samples were treated with an aging-box at a temperature of 60 °C and a humidity of 90% under one atmospheric pressure for various days, the structures and properties of these experimental samples and the original composite samples were studied systematically. The results show that aging has some influences on the structures and properties of these aged samples. Compared with the structure of original composite samples, although no changes of the phases, functional groups, molecular weights and molecular weight distributions have been found among these aged samples, the crystallinity degrees of these aged samples are different and they increase slightly with the increasing of aging time. Additionally, Cu(II) species have been formed in the surface and subsurface of the experimental composite samples, and their concentrations increase with the increasing of accelerated aging time. Compared with the properties of original composite samples, with the increasing of aging time, their tensile strengths and their elastic moduli increase initially and then level off, their glass-transition temperatures increase and elongations at break decrease slightly, and their cupric ion release rates decrease slightly. These results are very important for us to design both storage time and lifespan of the Cu/LDPE composite Cu-IUDs for the future clinical use.