Abstract: Aluminium tube evaporator is an important component in the cold-producing system of refrigerator,and the Aluminium tube corrosion leakage will cause the system failure.The corrosion feature and causes are investigated in the paper by a scanning electronic microscopy,metallographic microscopy,elemental analysis,dissolving test of related polyurethane foam and stress corrosion test.The corrosion develops in the tube wall from external to internal side,in the feature of grain boundary corrosion.Elemental analysis by energy dispersion spectrum indicates that the content of impurities Fe is much higher in corrosive region than in standard sample and its distribution is not uniform,which shall be a internal cause for the corrosion.External cause for corrosion shall be due to the incomplete coats on the tube and small amount of corrosive medium from the polyurethane foam.In addition,some workshop scratches may accelerate the corrosion.Based on the failure analysis,some quality improvement measures are presented and a satisfactory result is received with the practice of the measures.