Abstract: The effect of pre-deformation on the precipitation behaviors of Al-Mg-Si-Cu alloy was studied by DSC, mechanical property measurement and TEM. The results show that, the GP zone dissolution rate decreases with increasing pre-deformation during the slow heating up process for the pre-aged alloy, the corresponding activation energies of 0%, 5% and 15% pre-deformed alloy calculated by Avrami-Johnson-Mehl method are 137.1KJ/mol, 189.5KJ/mol and 141.3KJ/mol, respectively. If the pre-deformed alloys are directly bake hardened at 185℃for 20min, precipitation and bake hardening increment can be greatly improved by pre-deformation (the highest bake hardening increment is 160MPa), but the bake hardening increment rate gradually decreases if the pre-deformation is above 10%. In addition, the GP zone dissolution rates of pre-deformed alloys after bake hardening treatment are much lower when the heat treatment temperatures are below one certain value, but if the treatment temperatures above it, the corresponding GP zone dissolution rates are higher than that of alloy without pre-deformation, finally, the activation energy changes from high value to low value even can be observed in the ln[(dY/dT)φ/f(Y)]-1/T curve. For the β〃precipitation in the alloys, with increasing pre-deformation, its activation energy gradually decreases, corresponding gradually increase of precipitation rate, all of these results are in good agreement with the TEM microstructure evolution.