Abstract: Aging of cables not only affects transmission efficiency and stability, but also brings safety risks. Using accelerated aging test methods, thermal-oxidative aging treatment of irradiated crosslinked flame retardant polyolefin cables was conducted at 180 °C, mechanical properties, dielectric properties, and structural changes at different aging states were studied, and useful life at different temperatures was calculated by using Arrhenius equation. Results showed that elongation at break decreases with increase of aging time at 180 °C, and tensile strength increases slightly and then decreases gradually. Shore hardness increased from 90 to 96 HA with increase of aging time. Dielectric constant, dielectric loss tangent and conductivity of cables under different aging times also increased gradually with increase of aging time. Based on life assessment, useful life of cables at 105, 90, 80, and 70 ℃ were 6.3, 28.3, 83.0, and 258.9 years.