To enhance the bonding strength between diamond coating and matrix, chemical vapor deposition was used to deposit diamond coatings on ordinary and diamond-impregnated cemented carbides, separately. SEM, Raman and indentation tests were used to analyze and compare the coatings. Results show that both homoepitaxial and heteroepitaxial growths of diamond coating could be found on the diamond-impregnated cemented carbide substrate, and that the coating deposited on diamond-impregnated cemented carbide substrate performs high diamond nucleation rate, uniform crystal size, and flat coating surface. It is also found that the bonding strength between diamond coating and diamond-impregnated cemented carbide is higher than that between coating and ordinary substrate, which will greatly expand the application of diamond coating.