Fe-Mn-Al-C steel has excellent weight reduction potential. In this study, the microstructure and mechanical properties of Fe-25Mn-11Al-1.0C steel after solution treatment at 1050 °C and aging at 450~650 °C are studied. The results show that with the increase of aging temperature, the strength increases first and then decreases. The plasticity and strength show a trade-off relationship. With the increase of the aging temperature, the plasticity first decreases and then increases. The above-mentioned changes in mechanical properties are closely related to the changes in the morphology and distribution of κ-carbides during the aging process. In general, the precipitation of κ-carbides is beneficial to obtain higher strength, but has a detrimental effect on plasticity.