Abstract: The interface reactions of the metal-doped diamond coatings, deposited by chemical vapor deposition (CVD), and substrate of impregnated diamond bit (IDB) were mathematically modeled and theoretically analyzed in First Principle Calculation based on density functional theory. The influence of the metal dopants (Co, Fe, Cu and Ti) on the electronic structures, atomic structures and bonding energy at the interface was investigated. The calculated results show that the impact of dopants on interfacial adhesion can be listed in a descending order: Co > Fe > Cu and Ti. For example, Cu and Ti promote formation of carbide and diamond like C-C bond at the interface in diamond film growth, resulting in strong interfacial adhesion; Co and Fe dopants have a large charge transfer ability but an interface adhesion weaker than that of Cu and Ti. We suggest that the calculation be of some technological interest in surface modification of IDB.