The stress corrosion cracking threshould stress intensity Kiscc and the rate of crack propagation da/dt of aluminum alloys LY12cz in the 3.5% NaCl aqueous solution，in saturated NaCl aqueous solution and in 3.5% NaCl aqueous solution of the containing combinated inhibitor are measured and studied by DCB specimen in this paper，the effect of Cl^- concentration and the combinated inhibitor have been analyzed in details. Through scanning electron microscopic fractography，it is shown that the fracture aspects of stress corrosion crack of aluminum a11oys LY12cz in contained Cl^- aqueous solution is a intergranular crack and the fracture feature is that of stone. Although the properties of stress corrosion cracking can be improved so as to decrease the rate of crack propagation abviously by the above mentioned combinated inhibitor，it can not be changed for the fracture feature.