The chloride-containing phases other than crystalline oxychloride in magnesium oxychloride cement（MOC） is proposed as alcohol leachable chloride， which can be used as an evaluation index of the properties and quality of magnesium oxychloride cement and its industrial products. Alcohol leachable chloride ion content（ALC） can be determined by conductivity method. Based on the principle of physical chemistry and a large number of experiments， the mathematical relationship between the conductivity of the magnesium chloride-anhydrous ethanol solution and the concentration of chloride ion in the range of 0.001 0-0.144 0 mol/L was established， and the associated parameters and specific test procedures of the conductivity method were proposed. By comparison of the test results of conductivity method and mercurimetric method， it can be shown that the conductivity method can be applied to accurately determine ALC of the hardened magnesium oxychloride cement paste and its industrial products. Conductivity method has the advantages of accurate results and simple operation.