As a type of special composite, Polycrystalline Diamond Compacts(PDC) has been increasingly applied in machining hard and abrasive materials, because of its superior physical properties. However, diamond is a non-metal materials, it is different from metals or alloys in intensity, hardness, elastic modulus and structure. Especially the interfacial energy is high between diamond and metals or alloys, resulting in the difficulty of most of metals or alloys to effectively wet. Due to feeblish interfacial bonding, Polycrystalline Diamond Compacts often ruptured and broke off during its application, thus increase drilling cost and reducing its range of application. Therefore, to study interface bonding between diamond and metals or alloy and its compounding mechanism are of great importance.In light of the present state and existing problems of PDC study at home and abroad, on the basis of tutor"s right guidance and the predecessor"s studying, The author conducts an investigation into the research topic in this paper by relying on Hunan province natural science fund item-A study on interface and it"s compounding mechanism of Polycrystalline Diamond Compacts(serial number:OOJJY2044). The following research work has been completed by SEM analysis, EDS analysis, XRD analysis, TEM analysis, TG-DTA analysis. It shows that:1.Φ20mm PDC have been synthesized at ultra-high temperature and ultra-high pressure, And the reaction vessels of 4Φ 40mm for synthesizingΦ 34mm PDC is designed.2. Based on the analysis of the past sintering theories, the paper has summarized and analyzed the reciprocity of diamond-cobalt in the process of ultra-high pressure and ultra-high temperature sintering, and advanced systemic theory on diamond fluid activated strengthen sintering under ultra-high pressure and temperature, namely, the plastic flowing, the Recrystallization and regrowth of diamond, the medi-bonding.3. Cobalt acts as the binder. The paper has studied s interfacial microstructure, interfacial reaction, the diffusing rule and action mechanism of cobalt and the interface influence on performances of PDC.It shows that:(1) The bonding interface between WC-Co matrix and diamond layer was not clear, and occurs in the form of WC-Co-D bonding, that is to say, there is a thin cobalt-enriched area. The cobalt content in the interface is higher by the process of mixture sintering of diamond and cobalt than by the process of Sweep Through Catalyzed Recrystallization sintering(STCR).(2) Cobalt distributes equably between diamond grains by sintering of Sweep Through Catalyzed Recrystallization, the intergranular has formed firm bonding of D-D; but the intergranular has formed firm bonding of D-Co-D by mixture sintering of diamond and cobalt, and cobalt is basically distributed as laminated gangue along grain boundary.(3) The contents of WC, Co2C, Co3C, 77-Co3W3C in grain boundary are higher by sintering of Sweep Through Catalyzed Recrystallization than by mixture sintering of diamond and cobalt, with sintering temperature increasing, the eutectic mixture of cobalt and graphite CoxC is reduced gradually.(4) The grain boundary is simply the surface at which the regrowth fronts expanding from the original grains met during manufacture of the compact. The grain boundary is quite irregular, and there is no simple orientation relationship, exists in a high-angle grain boundary. The small-angle grain boundary can be observed in a high-angle grain boundary, and it is made up of dislocations. There are a lot of crystal defects in grain boundary, this defects are dislocations and twins. At the same time, there is a trivial cobalt inclusions and graphite inclusions.(5) The heat stress and the heat resistance of PDC depend on the binder and the structure of reactants which were formed by reaction of the binders to diamond in grain boundary.