A parameter, notch insensitivity factor, has been derived in order to assess the stress concentration sensitivity of Al-Li based alloys. The effect of impurities and Ce element on the stress concentration sensitivity of Al-Li-Cu-Zr, Al-Li-Cu-Mg-Zr and Al-Li-Mg-Zr alloy sheets has been investigated and the dependence of the stress concentration sensitivity on the mechanical properties and microstructural parameters discussed. Deleterious impurities can enhance the stress concentration sensitivity especially for the conventional impurities in Al-Li-Cu-Mg-Zr alloy and for the alkali metal impurities in Al-Li-Cu-Zr alloy. Suitable Ce microalloying can reduce the stress concentration sensitivity to a certain degree and the benefit is more significant to the Al-Li-Cu-Zr alloy rich in the conventional impurities. When varying the composition systems, impurity kinds, impurity content, Ce element concentration and heat treating process makes the yield strength increase, fracture toughness decrease, partial recrystallised volume rise and grain size increase, the stress concentration sensitivity usually tends to increase. A special attention should be paid to the practical application of Al-Li alloys because there generally is high stress concentration sensitivity for the alloys as compared with conventional aluminum alloys.