Abstract: To achieve good combination of strength and corrosion resistance, the tensile test and accelerated corrosion test were used to study the effect of single-stage aging at 180-210 ℃ for 110 h on the tensile properties and intergranular corrosion sensitivity of an Al-Mg-Si-Cu alloys.The results show that with the increase of aging time, the alloy strength firstly increases and then decreases, the elongation decreases gradually, the intergranular corrosion depth imcreases first and then decreases, and the corrosion mode changes from intergranular corrosion to uniform corrosion. With increase of the aging temperature, the hardening and softening rate of the alloy increases gradually. After 200 ℃/6 h single-stage aging, the alloy not only has no intergranular corrision sensitivity, but also has high tensile properties, the tensile strength, the yield strength and elongation of alloy are 374 MPa, 359 MPa and 9.9 % respectively, accompanied by uniform corrosion. Transmission electron microscopy observations show that the matrix precipitates of the alloy for single aged at 200 ℃ for 6 h are Q' and β' phases and grain boundary precipitates are spherical and discontinuously distributed.This precipitation characteristic gives the alloy high strength and intergranular corrosion resistance.