The effects of trace rare earth element Gd on the microstructures and corrosion resistance of 7056 aluminum alloy were investigated by intergranular corrosion（IGC），stress corrosion crack（SCC） and electrochemical corrosion tests, combined with optical microscopy（OM），scanning electron microscopy（SEM） and transmission electron microscopy（TEM）. The experimental results showed that the addition of 0.11% Gd to 7056 aluminum alloy forms L12-Al3（Gd，Zr） dispersion phase, which improved the recrystallization resistance of the alloy by strongly hindering the movement of dislocation and grain-boundary, and allowed the matrix to retain more fine subgrain structure. Compared with the large-angle grain boundary, the corrosion potential difference between the subgrain boundary and the crystal was smaller，and the corrosion driving force was reduced. Compared with 7056 aluminum alloy，7056-Gd aluminum alloy had greater resistance to stress corrosion crack. Its critical stress intensity factor is increased from 5.45 MPa·m1/2 to 10.59 MPa·m1/2. The results of open circuit potential（OCP），electrochemical impedance spectroscopy （EIS） and cyclic polarization curves of the two alloys are consistent, indicating that 7056-Gd aluminum alloy has higher corrosion resistance.