Retrogression characteristics of a novel Al-Cu-Li-X alloy of 2A97 were studied by hardness testing, transmission electron microscopy (TEM), and differential scanning calorimetry (DSC). The retrogression treatments of aging at 155°C for 12 h followed by aging at 220 and 240°C were chosen by determining the peak temperature of δ’ precipitation at 230°C by DSC. The retrogression treatment at a lower temperature of 220°C causes the precipitation and coarsening of δ’ and θ’ phases in the matrix, resulting in an increase in hardness. Retrogression at a higher temperature of 240°C causes the dissolution and coarsening of δ’ and θ’ precipitates in the matrix and on the grain boundaries, resulting in a decrease in hardness. Microstructural changes upon retrogression including the appearance of equilibrium precipitates such as T1, T2, δ’, and θ are confirmed by the selected area electron diffraction and the bright and dark field image analysis. Retrogression characteristics of a novel Al-Cu-Li-X alloy of 2A97 were studied by hardness testing, transmission electron microscopy (TEM), and differential scanning calorimetry (DSC). The retrogression treatments of aging at 155 ° C for 12 h followed by aging at 220 and 240 ° C were chosen determined by the peak temperature of δ ’precipitation at 230 ° C by DSC. The retrogression treatment at a lower temperature of 220 ° C causes the precipitation and coarsening of δ’ and θ ’phases in the matrix, resulting in an increase in hardness. Retrogression at a higher temperature of 240 ° C causes the dissolution and coarsening of δ ’and θ’ precipitates in the matrix and on the grain boundaries, resulting in a decrease in hardness. Microstructural changes upon retrogression including the appearance of equilibrium precipitates such as T1, T2, δ ’, and θ are confirmed by the selected area electron diffraction and the bright and dark field image analysis.