Abstract: This Paper deals with the corrosion behavior of C/Al composite manufactured by Na-K method.A comparison is made between the corrosion behavior and that of the composite manufactured by CVD method.Immersed in either distilled water or 3.5% salt solution for 14 days, two kinds of materials metioned above corroded all severely.A rough surface has harmful effects on the corrosion of composites. The exposure to air for a long lime will result in the corrosion of the composites at defect zones (grain boundary, C-Al interface etc.).