A Cr layer with a thickness of 150 nm was successfully deposited on the surface of diamond particles using the de magnetron sputtering technique. AES analysis indicated that the Cr layer reacted with diamond particle to form Cr2C3 carbide species on the interface during the deposition. With the rising of deposition power, the interface diffusion between Cr layer and diamond substrate increased. The interface diffusion and reaction between the Cr layer and diamond substrate were promoted significantly by an annealing treatment at a temperature range from 300 to 600 degreesC in a ultrahigh vacuum (UHV). When the annealing temperature was below 500 degreesC and annealing time was less than 4 h. CrC carbide species were formed on the interface. Higher temperature and longer time resulted in a Cr2C carbide interlayer. The carbide species of Cr2C was resulted from the interface diffusion and reaction which can be intensified significantly with raising the annealing temperature and time. The depletion of carbon atoms from diamond substrate and the diffusion of carbon controlled the formation of carbide layer. The apparent activation energy of interface diffusion and reaction was about 38.91kJ/mol. The interface diffusion and reaction can be impeded by low vacuum.