Abstract: A number of studies on the behaviours of aluminium/graphite composite wires after exposure to the hygrothermal environment have been carried out. It is indicated that the water （mpisture） penetrating into the composites would cause the weight gain, hydrolysis of aluminium carbide and dissolve of aluminium matrix, which would lead to the weakening of interface bond and variation of tensile strength. It is harmful to behaviours of composite wires in hygrothermal environment when a large amount of aluminium carbide exsits. Therefore, it is suggested that the considerations of preventing a large amount of aluminium carbide formation or some protective coatings are very necessary.