Three pre-aging treatments of natural aging, artificial under-aging and artificial peak-aging were chosen to systematically investigate the influence of pre-aging on the corrosion resistance and microstructure of an Al-1.0Mg-0.5Si-0.8Cu alloy produced by combined cold-rolling and aging process using hardness measurement, intergranular corrosion test, slow strain rate technique, and transmission electron microscopy （TEM）. The results show that pre-aging can tune the hardness and corrosion resistance of the alloy. Among the three pre-aging treatments, the artificial peak-aging treatment results in the optimal combination of hardness（being 159 HV） and corrosion resistance（with the maximum intergranular corrosion depth of 55 μm and the stress corrosion cracking susceptibility index Iδ of 8.3%）. The TEM results reveal that the high density of dislocations efficiently enhances the hardness of the alloy. Numerous nano-sized Cu-rich lath-like Q" precipitates or curved continuous precipitates are distributed in the matrix, which eliminate the formation of grain boundary precipitates and greatly reduce the electrochemical potential difference between the matrix and PFZ，consequently significantly improving the corrosion resistance of the alloy. In the alloys pre-aged by natural aging, artificial under-aging and artificial peak-aging, the degree of precipitation in the matrix increases in sequence, so that the electrochemical potential difference between the matrix and PFZ decreases in sequence. Therefore, the corrosion resistance of the alloy is improved in sequence.