Due to the higher surface energy a diamond is hard to combine with the metal matrix of the cutting tool that is molded by hot-press. So the diamonds are easy to fall off when the cutting tool is under higher cutting loads, which leades to decrease the service life of the cutting tool. In order to deal with the above problem the technologies of chemical plating, chemical plating + duplex plating and salt-bath plating are adopted in this experiment. For increasing combining strength, improving the surface qualities of the cutting tool and prolonging their service life, the finer structure, better combining strength and definite thickness of plating layers on the diamond surface are obtained. A suitable pretreatment technics before the plating of diamond is found by the experiments. The best prescriptions and technical parameter of plating Ni-W-P are also confirmed. The advanced testing methods such as stereoscope, scanning electron microscopy (SEM) , electron probe microanalyzer (EPMA) , X-ray diffraction (XRD) and so on are adopted to analyze the microstructure, phase structures and ingredient of the surface layer of diamond after plating and heat treatment and find the dependences of the structures and performances out. At the same time, the forming process and mechanism, microstructure, surface appearance, composition distribution, phase structure and related performances of the duplex plating layers which form after plating Ni-W-P and duplex plating Ni-Ti-Re are studied. Otherwise, the Cr and Ti plating layers on diamonds are plated by suitable prescription. The related structure and performance of these plating layers are also studied. In this process, the reaction mechanisms of the every plating layers are discussed.The results show that the finer plating layers and well-distributed structure on the diamond surface are formed after the plating or the plating + duplex plating.