Abstract: The present paper has dealt with the changes of interface state between diamond and alloy by interface reaction between copper-based alloy, into which strong carbide forming elements were addcd, and diamond surface under the condition of liquid phase with a result of achieving welding with diamond. Furthermore, the model of the metallization of diamond surface and technical process have been put forward.The diamond particles with metallized surface have much the same sinterability, weldability and electrical conductibility (for electroplating)as common metal particles.The binding force of interface between powder metallurgical or electroplated metal matrix and diamond particles can be strengthened and the quality of diamond tools can be greatly improved.