In this study, the age-hardening behavior of severely-deformed and then artificially-aged A2099 Al-Li-Cu alloy has been investigated by Vickers hardness test, tensile test and transmission electron microscopy (TEM). The combined processing of accumulative roll bonding (ARB) and aging treatment at 373 K for 2419 ks resulted in the highest hardness (~190 HV) for the 5-cycled ARB sample with an age-hardenability of 37±2 HV. For the 2-cycled ARB sample with the aging treatment, the ultimate tensile strength and elongation to failure reached 553 MPa and 7%, which are greater than those of the ARB sample without aging treatment (i.e., 442 MPa and 1%). The corresponding TEM microstructures suggested that the refined '-Al 3 Li particles formed by spinodal decomposition are responsible not only for the higher hardness and strength but also for the optimized strength-ductility balance. Therefore, our proposed strategy; i.e. "take advantage of spinodal decomposition", is regarded as a convincing approach to induce nanosized precipitates within ultrafine grains for optimizing the strength-ductility balance.