This study examines the impact of aging at 600 °C on the tensile properties of 0.3NbFeCrAl alloy at various temperatures, including room temperature (RT), 300 °C, 350 °C, and 400 °C, as well as the corresponding changes in microstructure. Results demonstrate that as aging time increases, the grain size remains relatively stable, while the amount of precipitate gradually increases and becomes uniformly distributed. The tensile strength (R_m) also increases steadily with aging time, reaching its maximum after 1000 h of aging. This can be attributed to the precipitation strengthening effect of the Laves phase after 1000 h of aging. The yield strength (R_p0.2) remains constant when the specimen is stretched at room temperature, but gradually increases with both the stretching temperature and aging time. Additionally, the section shrinkage ratio (Z) exhibits a decreasing trend with aging time, except for stretching at room temperature. Nevertheless, Z remains above 50% in all other cases, indicating that the toughness of the aged specimens is maintained well. While fracture shrinkage is significant for tensile tests at RT, it exhibits minimal change with increasing aging time. Furthermore, a notable increase in the number of dimples and a decrease in their size is observed on the tensile fracture surface with aging.