Abstract: The high-strength 2A97 Al-Cu-Li-X alloys were investigated for the pre-aging effect on their mechanical properties and microstructures by means of tensile test, TEM and SEM. The results showed that the double-aging effect can enhance the alloys' plasticity due to pre-aging after quenching and quenching distortion, with the strength slightly lowers. The dislocation loops due to pre-aging after quenching distortion and the dislocation brought about by the distortion have the same effect, i.e. increasing the amount of T1(Al2CuLi) phases in matrix to distribute them more evenly. The polyphase microstructure consisting of T1, δ′ and θ′ was found due to double-aging after quenching distortion, with the size of T1 precipitates on grain boundary decrease due to pre-aging. Dislocation loops and vacancy clusters caused by pre-aging may nucleate δ′ and T1 in matrix with limited amount after quenching, and the pre-aging effect accelerates the formation of clusters of solute atoms, and increases the amount of nucleated δ′(Al3Li)/θ″ (Al2Cu) precipitates and make their sizes stable. After quenching the polyphase microstructure consisting of T1, δ′ and θ′/θ″ due to double-aging was found, where the amount of precipitates T1 on grain boundary decreases with δ′-free precipitation zones on the grain boundary narrowed clearly.