Abstract: Al-Mg series alloys are widely used in ship building and marine structures.However, Mg-rich phases with low corrosion potential can precipitate along the grain boundaries after in service, inducing stress corrosion cracking. The effects of 175 ℃/100 h sensitization on the Al-Mg phase precipitation behavior, intercrystalline corrosion, electrochemical behavior and stress corrosion cracking properties of AA5083 were studied, and the slow strain rate tensile test was used to study the sensitivity of stress corrosion cracking before and after sensitization. The results show that no intercrystalline corrosion and stress corrosion cracking occur in raw materials.After sensitization treatment, the 100 nm thick β'-Al₃Mg₂ or β-Al₃Mg₂ phase is precipitated at the grain boundary, resulting in serious intercrystalline corrosion, electrochemical corrosion and stress corrosion cracking of the material. The stress-corrosion cracking behavior of aluminum magnesium series alloy occurs under the synergistic action of the anode dissolution of the crack tip precipitate phase and the hydrogen embrittlement caused by the solution acidification.