Zinc oxide/low-density polyethylene (LDPE) nanocomposites were prepared for intrauterine devices. The change of Zn^2+ release rates of nanocomposites ( doped with various mass fractions of zinc oxide nanoparticles between 5wt% and 65 wt% ) for 264 days in a simulated uterine solution were investigated. The resuits show that initial burst phases are followed by near zero-order release phases. SEM technique was employed to observe the surface morphology of the 45wt% ZnO/ LDPE composite. Elements and phases on the surface of the nanocomposite after incubation were also analyzed by EDX and XRD respectively. The experimental results show that incrustation formation does not occur after incubation.