Abstract: X-ray developing barium sulfate nanoparticles (n-BaSO₄)/polyethylene (PE) composites were prepared by melt-blending. The dispersibility of aluminum coupling agent modified n-BaSO₄ (Al-n-BaSO₄) in PE matrix, mechanical properties and accelerated-aging properties of composites were investigated. The morphology, structure, mechanical properties and filler distribution of the products were characterized by XRD, FTIR, SEM and universal tensile testing machine. The results indicate that chemical bonding occurs between aluminum coupling agent and surface groups of n-BaSO₄. The Al-n-BaSO₄ nanoparticles disperse well in Al-n-BaSO₄/PE system, and the average portical size is less than 100 nm. The maximum tensile strength of Al-n-BaSO₄/PE composites is 11.87 MPa, flexural strength is 6.61 MPa, and elongation rate is 66.78%. After 14 weeks accelerated-aging experiment of Al-n-BaSO₄/PE composites in simulated uterine solution, the tensile strength of composites only decreases by 5%-15%. The Al-n-BaSO₄/PE composites are expected to use in human bodies for over 10 years.