Cs-corrected high-angle-annular-dark-field scanning-transmission-electron microscopy (Cs-corrected HAADF-STEM) was employed to examine the phases in Al-Cu-Li alloy (AA2050), including GP(T1), GP(θꞌꞌ) and GPB zones with their subsequent nanometer-sized products, T1 (Al2CuLi), θꞌ (Al2Cu), and S (Al2CuMg) precipitates, respectively. Under the peak-aging condition, some solute-atom enriched clusters could still be found, and the newly-formed nucleus of GP(θꞌꞌ) with a mono-layer {100} plane of Cu atoms occurred at the adjacent area of the joint between θꞌ and S precipitates or the edge of an individual S precipitate. The transition of a single Cu-layer GP(θꞌꞌ) → θꞌ was presumed to be transformation via in-situ nucleation. The developing GP(θꞌꞌ) zones and θꞌ precipitates were easily subjected to soft impingement. However, hard impingement between two variants of θꞌ presumably occurred, wherein one θꞌ variant precipitate was blocked out by the other θꞌ variant. As for the creep-ageing forming (CAF) treated sample, some precipitates of T1 and θꞌ were found to have the cutting characteristic on specific ledges.