The effects of trace Ce, Ag on the microstructure and mechanical properties of Al-Cu-Li alloy after thermal exposure have been investigated. It's found that the addition of Ce may lead to a slight increase in mechanical properties after thermal exposure at 107 degrees C. The stability of T, phase is enhanced by independent Ag addition and the combined additions of Ag and Ce,which results in higher strength compared with Ag-free alloy at 150 degrees C thermal exposure. However, at 200 degrees C exposure, a great number of theta' precipitates at the expense of T-1 may be responsible for higher tensile strength in the Ag-free alloy than that of the independent addition of Ag and combined additions of Ag and Ce alloys.