In this paper, we use molecular dynamics simulations to study the diffusion bonding of a Cu/Al interface. The interface analyzed is that between atomically smooth (001) crystalline planes of a Cu and an Al single crystals. The thickness of the transition layer of the bonded interface is obtained. The structural change of the interfacial region under different cooling rates is analyzed by means of the radial distribution function (RDF) and the pair analysis techniques. The interface assumes an amorphous structure upon initial mechanical pressing and remains amorphous if the subsequent cooling rate is high. At lower cooling rates, however, the interface structure becomes crystalline. The diffusion-bonded Cu/Al specimen is subjected to tensile loading and its strength is compared with those of single-crystalline Cu and single-crystalline Al of the same size along the same direction. Calculated results indicate that the specimen with the interface has a lower tensile strength and a lower ductility than the corresponding single-crystalline Cu and Al specimens.