Abstract: The effect of trace Sc on the intergranular corrosion properties of Al-Mg-Mn-Cr-Ti alloy was investigated by intergranular corrosion test, the the microstructure of samples was examined with OM, SEM and EDS. The experimental results show that the addition of trace Sc could decrease the intergranular corrosion sensitivity and refine the grain size of as-cast Al-Mg-Mn-Cr-Ti alloy. The addition of trace Sc could reduce the gathering of Fe, Si impurities around grain boundary and modify the morphology and distribution of β-phase. It is found that the addition of Sc has obvious effect on intergranular corrosion property of Al-Mg-Mn-Cr-Ti alloy because Sc reduces the electrochemical corrosion in grain boundary.