The effect of pre-deformation on the age hardening behaviors, tensile properties and precipitate characteristics of an Al-Cu-Mg alloy with a high Cu/Mg atomic ratio during 180℃ artificial ageing was investigated by using transmission electron microscopy (TEM), hardness test and tensile. The results show that room-temperature rolling of Al-Cu-Mg alloys with a thickness reduction of 10%~60% plus a subsequent artificial ageing (P-T6) can result in the strength increase of 32%~69% with elongation ranging from 6% to 13% compared with the conventional heat treatment process (T6). Transmission electron microscopy (TEM) revealed the main precipitates are Ω and θ′ phase in P-T6 condition instead of θ′ phase in T6 condition. Furthermore, the aspect ratio of Ω phase is much bigger than θ′ and the number of Ω phase reaches the total precipitates of 30% ~75%. Compared with θ′ phase, Ω phase processes better precipitation strengthening and thermal stability. Ω phase can form through deformation-induced-precipitating in Al-Cu-Mg alloys, while Ω phase does not precipitate in Mg-free Al-Cu alloys with or without pre-deformation.